Rain bird 51 rotor sticking down

[RhettMan]

I must contend that iv haven't seen very many rainbird risers stuck in the up position, now that I consider a brand variable to the recollection.

Iv had good luck with WD40WRSL, when thats the only issue.

Then again! I remind myself im getting away from the OP's specific model.

 

[Wet_Boots]

I remember when the me-too brass anti-backsplash impact heads from Nelson arrived on the market with their stainless steel spindles. Seeing those spindles made it clear that we were relieved of any expectation of ever repairing the impact mechanisms.