[Boyso]

I'm not familliar with ICS guns, but it could be many things.

Maybe the shimming that's too tight, battery that's too weak, aftermarket piston that doesn't fit well in the rails and cause jams, or simply motor that's not height adjusted.

Have you done any recent upgrade/downgrade that may have cause the problem?

I'd try with a quality battery first, then with a new motor + quality battery.