Every Gun I own Except for Sniper

[Owen Duff]

Okay, I own a UTG MP5 (before the MP5s stopped getting made for a little bit), a Sniper Rifle, a UTG pump action shotgun, an MP-44, and an M733. All are electric except for the sniper and shotgun.

And all except for the sniper and shotgun are broken. So, naturally, I need some help.

UTG MP-5:
According to two members of my team (Rapid Fire Airsoft) and a member of C7Viper's team, the gears on my MP-5 aren't matching up. After I fire it, it makes a grinding noise that seems almost as if the gun is kicking back at me. I've given the gun to my Captain for the time being, but I'm wondering if the gears not matching up is the problem, or if it's the motor.

Schmeisser MP-44 (Or STG-44, whatever you like):
Safety switch. It's a unique safety switch in which sliding a little knob back all of the way puts it on full auto, halfway pulled back is semi, and not pulled back at all is safety. However, when I put it on safety, it still fires a BB on semi if you pull the trigger. I have no idea what is causing that. So I need some help.

M733:
With a full battery, the thing still shoots extremely slow and lethargic. It used to fire at a decent ROF, and was a pretty well tweaked gun. However, now the stock has broken off, the ROF has significantly decreased, and I just don't like the iron sights. Ignore the last part, but what could be wrong with the ROF?

Help is needed, please and thank you.

[Steven Winkler]

Well, that's one he'll of a list. Troubleshooting through text is near impossible, but I'll give it my 2 cents anyways. 
The mp5 sounds like a damaged anti reversal latch, or latch spring. If it is, it will shoot fine(kinda) in full auto, but once you let off the trigger it will cycle back. Making a weird sorta wrrrrr sound. Most time it will also cause a double feed at the start. Easy fix, mp5's are V2 box's, and parts are easy to come by. 
The mp44, could be easy or impossible. No clue what the gearbox is for those(maybe a V3), but it could be that the external switch isint meshing correctly, or is meshing in the improper location, with the internal selector plate. You shouldnt have to tear the gearbox apart, but you will probably have to take the body apart to get to the switch. 
The m733, that's just an m4 right? Loss of ROF could be anything. Crap battery, aging motor, bad bushings/bearings, worn out gears, or dry, abrasive internals. It's just process of elimination with that one.
Best of luck.
Steve 

[Owen Duff]

Thanks. The Mp5 idea you have there sounds interesting. I'm going to ask some of my teammates about that one. The MP44... yeah... I don't know much about it either. I think I'll just have to live with it. And with the M733 (It's a small M4 with no rails, very bland and boring) it's not the battery. I don't think it would be aging, either. I've only had it for a little over a year.

[robert kinder]

the brand of the m733 could explain it lol im betting its a JG

[Owen Duff]

Yeah it is hahahaa. How did you know?

 

[robert kinder]

lol just an educated guess. if you wanna get rid of it let me know. i kinda want a m733

[Derek Falcon]

The issue you have with the MP44 actually seems to be rather common. I had one that did exactly the same, and a few of my teammates have reported the same thing with thiers. My guess is the selector plate might be off in them, but I didn't disassemble mine to figure it out, so I just exercised proper trigger discipline.

I'm more of a gas gun guy myself, shimming, V2/3/4/7 shaving piston teeth....ugh....I don't get all that. Give me a GBBR/pistol to work on any day (EXCEPT a WA pistol, urgh)...