Since you have removed the bases you may as well strip out the amps and give them a good clean out. I would check the solder joints and have a feel of the wiring. If any of it has gone brittle it may be worth replacing.

 Hope this helps!

 Llewelyn

Have you already removed the cloth covers?  Once you do you can see whether the foam around the midrange drivers has deteriorated.  That's likely you're primary concern before worrying about anything else.
 

Hi Austin...well i've already got the new foam surrounds off ebay..(goodhifi.com)....and we'll replace those if needed....just want to do a full cleaning, etc....thanks !!

Any further info is appreciated...

salut

i have 2 penta mk1's with foam rot - ialso purchased new rings from good hifi however the supplied rings seem to be too big, the inner edge would appear to need to fit a good half way down the cone and the ridge appears to not be in correct location - can you give details of your rings external , interanal , internal exterior ring and external of interior ring dimensions - as not sure if g/h supplied correct rings

tony s

Thanks for the info Stotty....i've just got the rings and have not tried to fit them yet......

I'll check on them and get back to you.....i'm concerned now !!

Hi Austin - i take your point but the rings supplied to me are compared to the original penta units below

Outer diam                   penta 77.5   goodhifi  77.0

outer(inner) diam           penta  74.5  good hifi  67.5

inner(outer) diam           penta  58.0  good hifi  55.5

inner(inner) diam           penta 52.0   good hifi  46.0

the good hif rings have a flat aspect the penta has an angled one  -  I am worried the extra 3mm encroachment onto the cone will affect performance as will any stress/strain imposed by the flat ring being mounted at an angle  -  anyone out there with observations, comments etc.

There is another Ebay supplier, Germany/Austria based, more expensive, but the rings are similar to the penta dimensions however I am currently trying to ascertain whether flat or angled  -  these are suggested for repair of Grundig units. 

link

link

As previously comments/advice would be most useful!

tony