Occasionally I run into a problem when using my selector switch. Sometimes the light does not come on when switching the selector to semi. Also, sometimes the selector will work in semi, however it will not go to full auto, it is like there is something blocking the selector between semi and full auto. I have noticed that if you remove the mag and invert the empty mag well towards a light source, this seems to correct the problem. Could it be that the sensor is just dirty? I have not seen where the eye is to clean it. Could it be a completely different issue?

Thats a new one on me, but you may be correct in saying the 'eye' is dirty.

The main sensor is on the gear that sticks out of the top of the gearbox, and if you rotate it by hand you will eventualy see 1 or 2 little holes drilled in it which will be very close together - check to see if this has been clogged with debris. If so simply blow out or use a pin etc and give it another try.

The other option is that the electrical switch (part ELC-002 : Selector swith board) which connects the selector to the ECU at the front of the gear box has worn and will need replacing. A VERY SIMPLE job as it simply connects to the ECU with a small plug which you simply push in, and it attcched to the gearbox via 4 pins that are moulded onto the side of the gearbox casing, again simply push fit.

The part in the UK is about £15 so its not a costly job either .

Let us all know how you get on .

Do you need to remove the ECU to clean the eye? I am not really seeing something that would be the sensor eye.

If you open your gun you have the lower receiver with the gearbox in it and the upper with the piston assembly.

On the top of the gearbox in the lower receiver you will have 2 gears sticking out. The bigger one of the two with the bigger teeth connects to the piston when the gun is closed which is half teeth and half smooth which is the gear we need to look at.

Spin the smaller gear that is next to this gear with your thumb (its quite stiff) and the larger gear will rotate. You should see 2 holes in the larger gear if you are looking side on to it (ie not from the top, but from the side as if your gun was lying on the floor). If there is debris within these 2 holes either blow out or use a pin, re-assemble and give it a try.

If not, back to the electrical switch I'm afraid.

If you get stuck let us know