OK.
Door grounded - issue out of the way.

If you are confident (with game off and unplugged) remove backglass) locate the connector J205 - it will be on the left hand side - lower corner I think.  There is screen printing in white of the numbers for each connector.  Some are printed either above or below the individual connector.

Carefully remove the connector and leave disconnected.

This is isolating the switches completely.  If the problem continues we may need to look at a fault on the MPU board.
If the problem goes away, there may be either a connector issue or wiring issue between J205 and coin interface board -> switches.

This is where a DMM (multimeter) will come in handy.  Don't stress if you havn't got one yet.

This fixed the problem on my Getaway, so if the above cannot isolate it, over to Humpalot!

Re the ramp - if its the metal part (1/2 way and near top) then it is normal.  I thought the same thing!
Supercharger sometimes going slow?  Does it speed up.  Mine sometimes starts of slow but speeds up quickly.  If not might be a magnet not plugged in or dead.  Plug and play fix on the magnets but we'll get your sound issue sorted first.