Fun game. If the seller knows what he's talking about (and tells the truth ) then it will be an easy fix.
But for example, I serviced one the other week, similar problems. The flippers didn't work and neither did the shooter. One of the fuses was blown on the PPB board, and after replacing it, the shooter coil locked on (the shooter coil was also burned, and wired the wrong way, and there was another burned coil in the coinbox).
After some measuring, it turned out one of the TIP36c's on the PPB board was fully shorted, and one of them had strange readings when measuring. I narrowed the issue down to just those two transistors, so I replaced them, and the game now works like a charm! Cheap and easy fix in itself, you just have to find the problem first...
So... It might be an easy fix, or there might be more to it.
I think they fetch about €1000-1100 here in The Netherlands, not sure if that translates well to the value in the UK.