First generation FX Crown

I would check out Ernest Rowes video about the regs 

https://www.youtube.com/watch?v=p-p-sGTJCiA&ab_channel=ErnestRowe.

There you can check and find out if it is really reg creep, and how to fix it. You have to be carefull you do not damage or scratch the reg piston when you take it out of the gun. Since you have to take the parts out anyway, you might aswell try polish the parts first, as it will be a cheaper solution, than bying a new reg.