[TenTec] Paragon II display freezing up

[designer]

 From time to time the display on my Paragon II goes blank (I think 
the VFO A light is still on). At that time, the audio still works - I 
can still hear the station I was listening to - but the tuning dial 
has no effect - like it has gone into "lock" mode and blanked the 
display.  Everything is fine once I restart.

I do have other rigs about and a computer, but I am not transmitting 
on another rig when this happens. Is this a sign of more problems to 
come? Is it a major problem to fix it?

The PS,  model 961, has a low hum. Hardly noticeable when computer 
fans are on - but clearly louder than the 937 and a small Samlex I 
have. Is that normal for that vintage technology or can replacing 
some parts quiet it down to "silent" level.

Thanks and 73,
Paul