ICS M4A1 half-gear issue

[vortex30]

Back Story: I bought my ICS M4A1 used and I've had a load of problems with it. First time using it the gears must have been misaligned and I grinded away my tappet plate and needed to install a whole new upper gearbox. Finally got it working and then some positions on the motor decided to die. Bought a new (cheap) motor and the thing was working great for the past few weeks. Let my friend use it, he didn't pull the trigger all the way back when shooting on semi-auto like I instructed him to and it stopped firing BBs, but still sounds good and healthy in terms of everything else.

I tried: charging the battery and making sure my mags were feeding BBs into the gun to no avail. Also checked for a BB jam but there aren't any.

So: I opened it up and noticed that the half-gear wasn't in the right position. It was half teeth and half smooth, so I spun it to all smooth showing, closed it back up and tried to fire a few rounds. Nothing comes out. Open it back up and the half gear is in the same position as when I first opened it. Put it right and try firing just once. Same position. So it seems that the first shot only spins the gear part of the way (or over spins it), and the subsequent shots do spin it properly (but because it's already in the wrong position it doesn't fire).

Does anyone have an idea as to what is going on and how I can fix this issue? Please provide a fairly substantial set of instructions as my knowledge of how these guns work isn't very good yet. Just got into airsoft recently and it's loads of fun but lordy are there ever a lot of issues, lol! One thing I don't get is why the very first shot also doesn't fire, but maybe the first shot never fires/isn't supposed to fire?

Thanks for reading and hopefully having some ideas to help me out here!!

[Kos-Mos]

Lots of possibilities here.

Can be a bad battery (as in damaged, not empty)
Can be a bad motor (cheap usually means cheap)
You probably installed an upgraded upper, which includes a stronger spring. You didn't need to change the whole mechbox, a 10$ tappet plate could have solved it
The shim job is probably bad since the gear ate your tappet plate. That can cause extra stress for the motor to turn
Your lower mechbox can be crooked. Happens sometimes, especially with older rifles as the quality control was not really great 10 years ago from ICS (they where making guns back in 1997)
If you forced the gun closed with the gears miss aligned, you can have broken everything mechanical in the gun (gears, piston, tappet plate, bushings/bearings, cut-off lever, ARL)

Releasing the trigger too soon does nothing if you don't open the receiver. When you do, you HAVE to re-align the gears by placing the flat section on top. Failure to do so WILL damage the gun.

[HKGhost]

just a little input, I've notice on the past few ICS M4 that I've worked on all had broke tappet plate. I've found out that the spring for the anti reversal latch sometimes fail. Either by being out of place or has no tension at all on the latch. Because of this fail, the gears would spin backward after a shot and smack into the tappet plate and piston breaking them. This is something you might want to look into.

[Pyrohair]

Does it make any grinding sound at all? The ICS M4 gear that connects with the motor gear (i forget the name of it at the moment) is notorious for breaking in the middle and allowing the Anti-Reversal part of the gear to not spin while the gear part does therefore hearing a wicked grinding sound. That's what happened with my ICS M4 and I fixed it by throwing in a new set of gears.

Also, right after I fixed the gun I noticed poor performance and speed with the gun. I suggest trying a 9.6v battery in there if it is not the problem of the gear. The 9.6 really improved the gun and it rips people to shreds now.

[vortex30]

Update: Over webcam tonight a friend who is much better versed in airsoft repairs (though still no expert) and I did some troubleshooting and managed to find what the problem is. The air nozzle had fallen off of the tappet plate. The reason for this is that it broke along the groove that the tappet plate fits into. So I need to buy a new air nozzle it seems. Anyone know a good website where I can find one that fits an ICS M4A1? Preferably a Canadian website. The gun model is an ICS-41 AI Retractable if this helps.

Also, in terms of repairs, what am I looking at here? Will it be necessary to dismantle the upper gear box to replace this part? Can someone point me to an extensive guide for doing this? I don't want to break anything or put it together wrong...

Thanks!

[Styrak]

If you don't know what you're doing you should get your friend with more experience, or a gundoctor, to fix it for you.

[Kos-Mos]

If you can do LEGOs, you can fix this.

You will have to remove 6 screws + the large one at the back of the upper mechbox.

Put a screw driver or something long in the hole at the rear to hold the spring/spring guide in place when you open.

You need the ICS nozzle unless you want to replace the whole hop-up units. Some say it works with regular M4 nozzle but my personal experience with ICS says otherwise.

Backwards for reassembly. Really ICS rifles are way too easy to work with.

[baker_Jeff]

Update your location, depending on where you are we can suggest places to purchase replacement ICS parts.