TM PSG-1 with issue

For sale TM PSG-1. Its issue is it will not fire with its de-cocking/cut off level installed. However when I remove the de-cocking/cut off lever from the gearbox it shoots flawlessly on full auto. I believe the problem to be the de-cocking lever spring . The only other issue is the cheekpad is not adjustable .
This PSG-1 has a King Arms Tappet Plate, a Madbull Ver.2 650mm Black Python tight bore barrel, G&G M82 Type Flash Suppressor, Systema Gears, Power FET , New Systema Motor, TM PSG-1 Bipod and a 70rd G3 Mag as well as its own 15rd mag. Its electric blowback and shoots at 327 fps. I am the second owner of this Psg-1 and it was never skirmished. Looking for 225 for this, an easy fix for someone with more time and patience than I do.