ls3020 cutting failure

[unravelled]

This machine is about 18 months old and has had light (hobby) use.
About a month ago it failed to cut, (though the head moved OK), but after a bit of knob twiddling went back to normal. I wondered then if it was a dirty multiturn pot, as turning it up full seemed to be part of the cure.
Since then it's happened a couple of times more, though tinkering seems to have got it going, but today it's been unresponsive to any plug reseating etc.
I had suspected the lid sensor, but that seems to switch OK.
When turned on the last working session, I thought I heard a slight "fizzing" from the electronics, but only short lived , and it cut OK.

There is a single red LED visible on the board at the front of the case, and 2 greens on the cased assembly on the bottom (psu?).

Are there any faultfinding resources handy? I'm happy to do some tinkering, as long as I know what I'm getting into.

Thanks

Dave

[PhillyDee]

If playing with the pot sorted it in the past, I would be tempted to replace the pot. However, a quick call to HPC on Monday might get you sorted. They will certainly sell you a pot!

[unravelled]

The pot seems to give a reasonable reading on a meter so I don't think it's that. It's more likely that the fiddling /opening closing the lid jogged something into operation.
Are there any other safety interlocks besidesthe lid switch?

Thanks

Dave

[PhillyDee]

There is a switch in the rear door, and a magnetic one on the front door. You could change this, but I cannot give you any tips on how to defeat them due to health and safety!