Check to see what mode it is in. It may be in three ball mode, just not allowing the third ball to escape. Second check the dwell. Many times you have to adjust it due to the season. (P.S. the dwell is basically the cycles on the gun, if making sure the bolt can keep up).
Yes
If this is happening you are losing gas. You need to fix your hoses. Make sure you have full pressure in your tank. If the problem persists, go to a paintball pro-shop and get a technician to look at the internals.
Take it to an airsmith or paintball tech.
Take it to a paintball field and have it looked at. Or be specific about he electrical problem.
It sounds like your tank is empty. You should go get refill it.
replace the seals
lube it and clean it, chances are that's what it needs, use paintball specific oil, no motor oil or wd-40
Read the manual, or be specific about the problem.
It depends whats wrong with it there's a lot of things that could be wrong with it
you get a better computer
If you are asking how to fix it: Unfortunately unless you can glue or seal it it, the gun will not work without the Black sear pin. You may have to buy a new receiver half.
oil it or shoot a squealer