Most of the Parker Repops are nearing 40 years of age, at this point. My own opinion (free!) is, that when we hear of a gun misfiring, there is a pretty good chance it is a Parker Repop. But, in fairness, it is past time for most of them to have a strip and clean.
Pretty extensive group of names who can do the job will come up right here, with just a little searching.

Good luck.

Best,
Ted