Coils in pinball machines sometimes burn and melt the plastic spool, there is no way to reuse or repair it. Rewinding a coil could be feasible but I did not find a place to buy the plastic spools to wind a new wire on. This design allows anyone to easily print a cheap and usable spool to rewind a coil. The design is valid for Bally machines but the sketchup files are provided so that anyone can adjust dimensions for other brands or bigger or longer coils. See pictures for complete setup, it works ! The material cost of plastic & wire is around $1 (a new coil is usually sold for $20).
Print both parts and adjust the top reel at the right distance and glue them together. Buy a reel of winding wire of the same diameter as the original, mount your printed spool on an axis, fit the axis in an electric screwdriver with speed control, attach the end of the wire into one of the three holes, slowly make the spool turn and carefully wind up your coil. Counting the wire turns is difficult, when the coil seems big enough, just weight it on a kitchen balance and compare with the burnt coil ! The third middle hole is for the experts who want to try a 2 windings coils for flipper control. Rivets should be crimped in each used hole to allow soldering, be careful the plastic melts ! Do not forget to insert the usual nylon sleeve inside the spool.