The lid I have now looks very, very cheap. No B&O on top like a BG 1200 lid and very thin plastic. But the lid is the last thing to care about, first I have to get it up running again.

Do you have pictures of the inside maybe? I'd like to check if it's complete, before I start looking for a belt, a cartridge etc.
How does it actually work? There isn't something marked "play" or any other hint.
 

(I'll upgrade my membership for the manual, but can you give a hint on how to open it?)

It's brother, the Acoustical 3100 sometimes shows up (more often than this one!) and sells for lots of money. Is it really that good?
 

Once you have power to it, all you do is lift up the arm from the retainer, there is a rod inside the retainer pillar which operates a fairly crude lever switch under the top of the plinth.

 When you lift this arm up, you should get a neon light show up in the little window on the front right. This neon illuminates the underside of the platter, which you can see because there is a mirror in view of this window. What you should see is a row of dots, which you use to get the platter to the exact speed as the flickering of the neon light acts as a strobe.

You adjust the speed via a knurled metal knob which is at the front right of the turntable.

There is a similar knurled metal knob on the front left of the turntable, this is used to change the speed from 33 to 45. Its very simply made affair, it hooks the belt to a differant pulley.

If you want to get at the belt, then look on the top metal surround faschia that goes around the platter. You will see small metal machine screws, you unfasten them and this fascia just lifts away and you can easily see the 33/45 speed change mechanism on the left and also see the belt.

If it is doing nothing, then the chances are that it will be something to do with that lever switch, or the actuator rod that runs from the arm support, it may be gummed in place, or the contacts of the switch may be tarnished.

This turntable is a very simple thing in terms of electrics, it's possible that the fine speed controller on the right hand front is broken, and you will need a fairly heavy duty rheostat to replace it, but it should not be hard to obtain something that will do the job.

Ok, it's alive! When the arm is moved to the center it starts turning and the light turns on (already more than I expected).

I don'n know if it's possible to change the rpm a lot, but at the moment it's only at 27 rpm when in 33 rpm mode.

It seems there is an adaptor mounted for a different type of element than the original sp ?? ones.

There are also 2, one on each side of the platter, holes where screws seem to be missing. The deck is also not really well mounted to it's wooden chassis, but I can't see anything that a screw could hold underneath.