For the 2500, your trigger piece is probably cracking up. Here are 2 write-ups on this very common problem.
http://www.isoaker.com/Armoury/Repair/r ... igger.htmlhttp://www.sscentral.org/repairs/snapped_trigger.htmlMake sure its well reinforced. You can add metal plating to the sides in addition to or instead of the center. Just be sure it moves efficiently since the space is usually confined in the case. (which you can solve with a dremel or a little sand paper)
For the SS 100, that "handle" is more like a grip for the reservoir. With some good glue (like the putty that isoaker mentioned) you can fix it up, or find something new to use.
Now, in most cases, you'll need to open up the 2500, but if you can find a way to keep the trigger together (bent back to its original position), and hold it there for the glue, you won't have to open it up. If the trigger piece is not the problem, then you'll have to open it up and check the valve. Is there any pressure stuck inside? You'll want that out as soon as you can.