Vintage Gruen Precision Stainless Steel Watch Swiss 510 RSS? NOT RUNNING

**NOT RUNNING** The movement is stuck fully wound, the crown won’t turn any further & it won’t run. I am unable to get the caseback off, but based on some Gruen’s I’ve seen with the same exact Dial & case, I believe it houses the 510 RSS movement, but I cannot guarantee that. The dial is relatively clean for the age it is, but it does have some aging that I tried to highlight in the photos. The all stainless steel case is very sharp, but does have scratches here and there. I don’t believe it has ever been polished before. Crystal has some small scratches on it, but is in good condition.