Hi tmel

So did you solve the leak? The reason I ask is that adding a bunch of glue probably will only be a temporary deal and is never recommended. If you are getting
juice on the top of the battery it is likely that there is a leak coming from the tubing where it slides on to the metal nipple. If this is the case, you can pull the tubing off the nipple, flip it around and slide what was the bottom of the tubing over the nipple. You can secure it with a small dot of super glue on the nipple before you put the tubing on it, but it isn't necessary unless it doesn't stay in place.
The sheath over the firing pin or positive battery contact is there to prevent shorts. johni is right, if a short occurs, your spring should collapse and drop the battery away from the positive contact. So you're not in danger, just more likely to have a short without the sheath. My advice is to contact Rob either by PM here or
call him. You can see if you can get some replacement material or just send it in for repair.
Keep us posted.
