Hi Sniper,
If the gun is under warranty, send it back, if you attempt to fix it yourself you will void the guarantee, by returning the gun, you and all other players that send in their defect Echo-1 guns, will force the manufacture to improve their QC Levels, this makes them Produce better guns, if not then handlers will drop them like a hot Potato, it´s a pain in the fourth point of contact for them to have to keep sending guns in for repairs, or Replacing them.
Handler Reputations are also damaged by selling guns that are constantly being returned for repairs, sooner or later their customer base starts to drop off, and when it hits them in the wallet, then changes start to happen.
If it is not under Guarantee, you are going to have to open the GB to fix the problem, it could be as simple as an ARL problem, or as bad as a destroyed Piston, Broken Gear tooth, Broken Spring, Switch Assembly Short.
By Saying that the GB is JAMMED, then I assume it is not doing a thing, just Locked Up.
The only way to fix it is to open the BOX, sorry.