So here is the story,

This machine is a friend's who plays it alot..and has friends that play it alot..and because I own a pinball machine hopes that I can fix it.
I however only know gameplan machines and know next to nothing about stern games so I seek any wisdom or advice from the experts of pinside. The following are problems and the order of which they occured.
1. The Hammer Magnet-I have looked on the site but found no mention of this issue. The machine has one of the new boards to fix the errors that occured with prevous boards, ie phantom hammer hits, and magnet not responding. Those are not an issue. What happens is the ball lands on the magnet, is locked, and the magnet lowers itself to the coffin area. Once the lowering mechanism stops, the ball is released and slids back to the metal bracket and not forward at all. It stays there, and even when the machine recognizes it can't remove it. I checked the wiring but nothing seems broken, rusted through or damaged.

2. The snake jaw-This is a more recent problem that I am troubled by. I ran the diagnostic check and was shown the following on the dotmatrix display:
50v/20v disabled
Jaw Coil () (x)Jaw switch
Latch coil () (x)latch switch
Eject Coil () () eject switch
The mouth no longer opens or closes and I am not sure what to do to fix this problem.

3. Shoot lane ejects 2 ball instead of one-When I ran a diagnostic, it displayed an image of what appeared to be balls but had teen number list on them. The first ball was only outlined, located near the shooter ramp. The next three in the through lane, I think that's what its called, where color and solid. The last was outlined, labeled 18 (I think) but not solid. The screen stated that a ball was missing but when a fourth ball was added, 2 would be ejected.

4. There is a fuse, I think that's what it's called under the playfield close to the front on the same side as the right flipper set up. It is brown and looks burn out. I intend to replace it but I am concerned that replacing it will not stop the actual cause. Would any of the issues above have encouraged such an outcome?

Any advice is appreciated.