Try checking out
www.classicairsoft.org in the workshop section.
However they are currently having some issues with the site though.
I have only accessed the site through a cellphone because of this.
The admins have been trying to resolve the issue.
Have you noticed any air leaks? Even minor ones?
Also how are your crush o-rings? I think this is the common cause of problems IIRC.
Has the airshaft collar slipped at all?
Which version is the kit that is in the gun?