Echo1 SCAR-L | Semi mode shoots full auto (and a few other problems)
 

Hi guys, I got into airsoft a few years back and i bought my first AEG last year. It was a sportsline Aftermath Broxa MP5, i got some help last time, and it has been great for me since. Anyways i bought a new gun because im starting to look for outdoor places to play. I got a used Echo1 SCAR - L with 8 mags and some accessories, however it was missing the rear iron sights. I bought Magpul MBUS sights for it and was shooting and noticed that the bb's flew out and then curved to the left. I just took out the barrel and hopup unit for inspection and realligned it just in case. But I think it was about a week after the purchase that for some reason my semi auto starting shooting full auto. Im not sure whats causing it. Can someone point me towards what i should check for and what else I can do to make sure the gun shoots strait? Im kinda hoping to do some productive changes before i put the thing back together for the 10th time, so i figured i would come back here for some help.

Echo 1 ASC T Gearbox Removal on youtube

Ok I got the gearbox out and reassembled it carefully with the gears in the right orientation. However the selector knobs are on a little loose now, im not sure if its because I damaged them or because in the process the screws came loose somewhere. How can I tighten them?

Edit: Ok something is definitely wrong now... the selector switches keep going out of alignment the right side gears keep slipping, and now semi gets locked up into safe and the switches are no longer parallel.

Sounds like its either a broken/worn selector plate or a worn cut off lever/worn sector gear.

The nub on the bottom of the sector gear + cut off lever controls semi auto

Maybe... but i just tired moving the entire selector plate manually and firing, and it still fired full auto. so its not the gear. the cut off lever doesnt look to be sticking either... could be internal? and the ambi gear on the right seems to be wobbleing because the slit where the shaft goes in got a little wider... possibly because of when i was prying out the gearbox. So i need to grab a new one.

Edit: Found a ghetto fix for the gear... I just cut a spring from a pen to about 4mm long and put it in to force the gear to stay flush with the gearbox so that it better engages the teeth, and now its fine =) but still full auto :(