Beomaster 1000 question

I have a Beomaster 1000 type 2316 I bought on a fleemarket in 1998 for the great sum of 80 DKR (~ 10,5€)

Fot the last 20 years my mother has used it now and the for a little radio listening but nut much, and now she use a Beosound 3 for this.

Therefore I’m considering gifting it away to another relative. Before doing that I wonder if it would be a good move to do some maintenence?

All in all the sound is good and clear. But when the volume is regulated a small scratch sound will appear.

Any ideas of what this can be related to?

Thanks in advance

Just trying to bump this question.

Also attaching some pictures of the beast