Strange SF M3 turn-on question

I bought a mint condition used M3. I have to screw the tailcap all the way in for it to turn on. This is the same whether for momentary or constant on. I do mean until the TC is hard against the body. I own many SFs and have never had one act like this. In an attempt to determine if I have a problem, I tried two different sets of cells, two different LAs, and two TCs. Same situation. The bezel is the stepped, mid-knurled, non-cren type. The impact foam springs right back to shape when I manually collapse the LA holder and release it. Any ideas?