Always list what machine you are playing with PC87 - someone on here probably has one...
As Dan said - lift the playfield at 45deg, then the far end of the wood can slide forward along the bracket. Be careful doing this - the playfield is made out of plywood, it's real easy to peel the top layer off!
Once the rear end has slid forward about 6in - you can then tip the playfield right back so it leans on the backbox. Have a good look at the guides (tracks) that the playfield sits in - there will be a "U" shape where you can sit the end of the playfield.
Put a towel on the backbox to avoid damage - AND put a towel underneath where you are soldering. (To catch any stray bits of solder)
If that's the only thing you have to fix - your're having a good day!