Ok......couple of measurements 

Ok......couple of measurements 

Another...

and another....

Thanks! ...but in this case I would have preferred actual dimensions in mm...

Oh well, as an optimist I gather that following plot of Beogram land (in light red) is available for redevelopment?😎

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I reckon that's good 10x10x4cm! That's plenty for a standard 50VA toroidal transformer, which is usually around 80-83mm in diameter and 35mm high.
The fuse box probably has to go as it is a total waste of space and can be redone in a quarter the size. Also it should leave enough space for a EMI/RFI line filter, which is something I'd strongly recommend this day and age considering the quality of the grid. A good branded filter costs some $10.- and is a worthwile investment and improvement.

I'd go with a standard 50VA toroidal transformer from digikey, Farnell, Mouser, etc. with 115V/230V input windings and 2x12V/2x2.08A secondary windings.
You connect the 2 secondaries in series to supply the 24V circuitry and use one 12V coil (just like a center tap) as supply for a 6V/1.5A LDO controller or, if you wish, for an adjustable LDO, eg. LM1086-adj. It needs just 2 capacitors and 2 resistors as external components and replaces the 2TR6. A small heatsink for safety might not be a bad idea too.

But before going down that road and ordering an actual replacement transformer, I suggest you really take some time and confirm the true space available -- preferrably in 3D, ie. make sure that there is no parts on the top cover that limit the available space or the height. I don't have a BG4000 on hand, so I can't check what really is or is not available.

Hi Craig,

My Beogram 4000 transformer ordeal was with my very first Beogram 4000 turntable back in 2015. 
My post showing it starts at the bottom of link.

Being in the USA I used a company link.  They had me work directly with their engineer to design what I needed and what would fit.
The resulting toroid was 71.1 mm in diameter and 35.5 mm in height.  A couple things to note about the design for mine are that I opted for a US-only voltage so I don't have the voltage selection for different countries.  I also didn't realize at the time that the 240 V secondary was necessary to power the neon strobe. It turned out quite well for me and that turntable is one I still use here at home. The link to my Beoworld post on it shows where I created an LED replacement for the strobe and that works great.  I remember the cost wasn't bad for a custom built transformer back in 2015.  About a year later Rudy used the Toroid company link for a Beomaster 4000.  That was quite a bit more expensive.

For your case it would be worth asking the Toroid company for an estimate. 
Someone else on the Beoworld Forum found

sonavor wrote:

The resulting toroid was 71.1 mm in diameter and 35.5 mm in height.  A couple things to note about the design for mine are that I opted for a US-only voltage so I don't have the voltage selection for different countries.

🤒 Thanks for this! Did you have them make a 60VA version or the more common 50VA?

I guess for Craig it's also best to use a single primary with 230V and without any taps - provided he opts for the custom-made solution that is. 230V covers all of Europe and more than half of the world market. The 220V secondary for the neon lamp is not needed at all with 220-240 mains. Some 45-55VA for the 24V secondary and 5-10VA for the 9V secondary will be perfectly fine. I would probably ask them to add a self-resetting thermo-fuse. It doesn't cost much and adds safety.
He can then disable the voltage selector, drop one of the primary fuses (which saves space and complexity!) and he has space for an additional line filter as I mentioned above.

It's no wonder that Rudy's transformer was quite a bit more expensive. It's a power-amp trafo with over 300VA and with all the taps from the original and they charge quite a bit for such gimmicks. Also, shipping prices from the US can be exorbitant. A few years back I ordered a refurbished motherboard for my notebook. Great price at barely USD30...but then the shipping was 100+  ... aaand to add insult to injury, since the total price was now over 100, I had to pay customs and duty! 😭

The rated primary current was designed for 0.34 A and a nominal supply of 120 +/- 10% and 60 Hz.  So that is a VA of up to about 45.
There are two secondaries -

UO: 24.1 Vrms
20.5 Vrms / 1.5 A 

UO: 10.1 Vrms
8.7 Vrms / 0.4 A

-sonavor

Found this that would fit the available dimensions....but the VA looks a little low at 30 and 1.25A output current? thing is I don't want to remove the voltage selector switch if I can avoid it....... 

Yes, that looks promising -- especially now that sonavor has confirmed that a transformer with a nominal power rating of 120 x 0.34 = 40.8VA is working just fine.

Don't worry too much about the nominal rating of 1.25A because it i just that, namely "nominal". Nominal values are based on international standards and norms and they are usually quite conservative, meaning there's quite some headroom left.

I do worry a bit more about the fact that the lower wattage may cause problems regarding interference between the 24V analog circuit and the 6V digital circuit....
Here's what I would do in order to make up my mind:
*) Measure the actual current on the 6V rail (AC measurement directly between the 10V winding and the bridge rectifier); not just a single measurement but a 15-30min measurement in normal operation. Your Fluke has a min/max/average function and that will help to assess the actual current drawn in normal operation. Let me know the average and max current you read there. And also the real AC output voltage under load...and the DC voltage at the emitter of 2TR6 under load! (The circuit diagram suggests a 6.7V DC output whereas the logic gate chips FCH131 and similar are spec'd with max 6.3V nominal supply voltage...and that makes me wonder...!)

*) Now do the same on the 24V winding at the AC side between coiland rectifier. I know that the current drawn on the 24V rail can go beyond 2A because of the solenoid and other power-hungry parts but that's only temporary and shouldn't affect the average load of the transformer - and that's what "nominal" power and current usually stand for in transformer specs.

Once we have those values we can make a reasonably safe decision on which way to go.

Craig wrote:

... thing is I don't want to remove the voltage selector switch if I can avoid it....... 

What do you mean by that? You don't want to lose the 115V/230V selection option? Well fine, then get the 115V/230V version: https://uk.farnell.com/vigortronix/vtx-146-050-212/50va-toroidal-transformer-2x12v/dp/2817651

But that sets you back a twenty quid ... and it's on backorder...😐
It's up to you, the decision is yours.