The arm thing sounds like the often seen tonearm lift problem.
We've had that here on the forum several times and I've uploaded a photo a couple of times to illustrate the point to lubricate but I can't seem to find it here now.

Martin

Couldn't find it using the search function here either but Google is my friend...

Of course, there can be several causes for the arm not
lifting, transport damage can't be ruled out,
but the above mentioned would be the first thing to check.

Playing a record after standing unused for a long time, it
will probably lower the arm correctly the first time but refuse to
lift it again or only lift very slowly. This is very common.
Since the signal is muted just before lifting the arm, you will
not be aware of the needle abrading on the record unless you actually
look at the arm while it (lifts and) returns.

As I understand it, this Beocenter was indeed left unused for years
and tested prior to the prize draw and I'm sure that it was working fine, playing
a record but maybe just one and the fault would not be obvious.
I would check the lift mechanism, it's not as hard as it seems, and
while in there check the center tap.

Martin