I have a P94 and I clean after shooting, lightly oil and have never had a malfunction of any sort. I bought it when I had my FFL and gave that up during Clintons dealer purge.
If I had to guess I'd say there was a problem with the spring or mags. I'd contact Ruger and let them deal with it. I'm bet they will fix for free or a small shipping fee. I can't figure why he would cover with grease in the first place. Isn't it stainless over aluminum?