I went to use my weedeater for the first time this season, and the
priming bulb has lost its spring. It doesn't pop back out, so I can't
prime the engine.

I took the bulb unit to the local small engine repair shop, and they
can't find a replacement for it.

Is there anything I can do to give the rubber back its spring?

What else can I do?
I hate to buy a new weedeater because of this tiny problem.
I replaced the fuel lines and filter last season, and it ran like
brand new.