Hi, I recently bought the above player on Ebay as a whim (I live in the UK).

With PAL discs, there are horizontal lines across the screen (not scan lines, they are about 1 inch apart) that sort of travel upwards on the screen. It doesn't put me off viewing, but you can see it in dark scenes.

With NTSC discs, it doesn't happen
Does anyone have any ideas what this is?

Sounds a bit like crosstalk but I'm unsure why it would only affect PAL only and not NTSC unless of course the NTSC disc your using is CAV?

Another possibility could be that the PAL disc is warped in which case there is little you can do.

To fix crosstalk you'll need to grab the service manual and follow the instructions within. Its been a while since I tweek my players CLD-2850 and 2950 so I can't remember off the top of my head the name of the pot you need to tweek. Of course without the proper test disc its a bit hit and miss but it can be done.

I would say a grounding issue, especially it you are playing a CAV recorded LD as you won't see the crosstalk with those. The PAL color signal is generated from a different they process and the 50HZ PAL verses 60Hz NTSC video signal. I have power supplies with capacitors starting to go bad cause bands across the screen and 50Hz power demands a little more from the capacitors.