Welcome to Pinside

You may have better fortune posting in he EM (electromechanical) Tech boards of this forum (them guys may not see a post in generic tech sections) https://pinside.com/pinball/forum/forum/electro-mechanical

here is a great video of getting into a pinball machine http://www.pinrepair.com/em/index1.htm#empartsvideo as part of an initially overwhelming amount of help: http://www.pinrepair.com/em/index1.htm

It sounds like you simply have a stuck play-field switch causing a bell coil to stick ... see what point increment is affected ( 1 point switch , 10 point switch , 100 point switch then manally try all the switches to see what one is stuck )

what area do you live , there are some pinball shows in the New England area USA with many hobbiests attending