You have a smart phone? Download the inclinometer app. There's several for free. It will set the correct pitch of your pin. As far as the play of the pin, I hope you like working on things because your about to. To me, from your description it sounds like you need a full tear down and shop job. All the signs are there. Not making it up the ramp=dirty flippers, pop bumpers not sensitive=dirty pop bumpers. When you take the glass off and run your hand over everything does your hand come away black? Yep. You guessed it, dirty. Time to start learning. Vid1900 has how to guides on rebuilding pop bumpers and flippers posted here on pinside. Good luck.

Oh, and take lots of pics before you take anything apart.

Can we get a pic of the ramp? Is there a way to rivet some sheet metal in place till a newer ramp is found? Set up a saved search on eBay for "ninja turtles pinball". Something will come up in the next few months.