Vintage Synth Repair

Hi,

I recently purchased a Moog Source from the US, which I now got 
rewired for 240V(thanks to Peter M. Blacket for the schematics!). To 
my relief the membrane switch panel seems to be intact, but there's 
another annoying problem: 

When I turn it on it's working fine for about 10-15 minutes, 
suddenly the keyboard goes crazy. It keeps playing the wrong notes 
from the wrong keys, and sometimes it can re-trigger the envelopes 
several times while pressing a key. Funnily this doesn't seem to 
affect the lowest octave. Sometimes it may start to work properly 
again after a couple of minutes. 

I wonder if this has something to do with the power supply 
generating heat, after a while it gets so hot that i almost burn my 
fingers on the back panel.

Please reply if anybody has a clue what may be the cause(and cure) 
of this problem. Somehow I got the feeling this is not the 
famous "crazy source" syndrome, since it looks like the previous 
owner did something to the digital regulators on the PSU board.

Thanks in advance,
Einar Ekstrom