HW/Weihrauch HW100 problem

Having an unexpected issue with my Weihrauch. It worked fine when last used in early fall. Still holding a good charge. It's been stored in an unheated room since last use. Today I went to use it, and it just "clicks". Nothing. Tried it twice. Tried topping it up to confirm that bottle gauge was indeed reading correctly. Same issue. Any suggestions?
 
Found my issue, sort of. The plastic stem on the poppet valve broke inside the action. Any suggestions on where I can find one ??
 

How do I order TWO of these ? Thanks for getting back with me !!