You'll have to remove the ramp.

Could you warm that plastic cover with a heat gun and bend it up a bit? No idea if that would work, just spitballing.

Just checked my TWD pro with a ball on a magnet wand. The ball only clears that plastic by about 1/8", so you won't have to move it much.

Judging from the pinched black wire insulation near the top screw/washer, it looks like someone's taken that ramp apart at some point. I wonder if maybe they didn't tighten the bottom two screws (which hold the cover) enough, and the cover is sagging. There's no washer/spacer between the cover and the ramp, they just mash right together, so any slack there might cause the cover to sag.

I dont own this game, but when you pull the playfield out and lift it into the service position, can you reach the nuts? I use a socket to hold the nut while I unscrew from the top. I think adding a couple nylon washers would work just fine to give you clearance. Might need longer screws, but all easily gotten at your local hardware store.