Transformer maintenance

I have an Audio technica AT-650 SUT which I bought NOS a couple of years ago but it must be easily 20 years old or more. It is the one with 4 adjustable positions 3, 20, 40 ohms and PASS. Apart from cleaning up the external contacts, might it be worthwhile opening it up and blowing out the cobwebs and spraying the insides and perhaps the switch mechanism with whatever or is it a question of "if it ain't broke, don't touch it".
Do transformers "lose their balls" or are they eternal ?

 

No, they are good pretty much forever, because the physics are intrinsic.

There are only a couple of caveats - power transformers not used for many years should be tested for leakage (in case the insulation has got damp/failed); and mu-metal screening cans can be made less effective if dropped/bashed about heavily. But that's about it IIRC.

 

Its worth doing the same for this unit too .....but as to spraying the insides I'd not ....

thats not to say you should not dust it and contact clean the rca sockets