Philips Norelco Replacement Head for Series 6000 Shavers

I bought these replacement shaver heads because after about 14+ months of use, the original heads on my razon began making strange scraping and clicking noises. I received these replacements and installed them fairly easily, and they worked fine. For about two weeks. Then they began making the same noises as the heads I had discarded. Interestingly, when I open the head unit and clean out the hair-shavings, when I then close the head and start to shave, it will work perfectly for anything from a few seconds to maybe 1 to 2 minutes, then I hear a scraping noise, like some small metal part slipped out of a groove and scraped along a surface,, then the clicking noises start up again. I'll admit, there's a chance this is the fault of the razor itself, and not the heads, but I've examined the mechanisms inside the head unit and can see nothing in there that seems off. VALUE FOR MONEY: If these only last 2 weeks without breaking down, then not very good. SHAVE QUALITY: Interestingly, even when it's making noise, it seems to do a good job of shaving I would be interested in hearing whether others have this same issue, or if I just got a bad lot.