Optos could be slightly dirty, the opto assembly might be loose ( screws). There are small boards under the playfield where the optos coonect to. Try Reseating those connectors . They will have thin wire that looks like speaker wire.

First go into switch edges test and pound on the playfield with a fist to see if any switches trigger. if any do, work on those switches first.

Each of the optical switches attach to a small opto board either under the playfield or behind the back panel. Want to say there's three of them. Each control two switches. Follow the wires from the optical switches under (or behind) the playfield to find the opto board they connect to. With power off, reseat each of the connectors on the opto board, power up, and retest. Problems could be the switches, the connectors or the opto board(s). You can swap opto boards around to narrow it down. New opto switches (with wires and connectors attached) as well as new opto boards should be available.

Sounds very similar to the problems I had with my WPT. In my case I traced it to poor contacts to the Opto Transmitter/Receiver Amplifier PCB mounted behind the playfield left-hand side.

I would clean the contacts best I could. Problem would go away a while but it always came back. Eventually I just put a new board in - they're not expensive.

That was a couple of months ago and no issues since.

Find that board first. Pull the playfield forward then lift the back and prop it up. The board which connects to the left ramp is on the left at the back.

There are 3 optos connected to it through some feeble Z connectors. Take them apart and clean both the pins and connectors. See if that solves the problem.

PS. I'm loving my WPT too. Great game.

Oops sorry Dizzy, haven't been on the forum for a while. I cleaned the pins with very fine wet-and-dry (grade 1000) and methylated spirits. I took the z connectors apart and wiped the contacts with meths too. Looks like none of that that matters now though.

Can you take the ramp somewhere to get it properly welded?