Hello, congrats on the S1a. I just picked up an old SV, which is basically the same camera, but with the 1000 speed and self timer. My test roll yielded similar results. I have posted a couple pics below. These were taken at 250 using the Sunny 16 (no meter). When I bought the camera, the slower speeds were defaulting to bulb, but after exercising the action a few times, they seemed to work normally. I didn't quibble due to the price, figuring I was still getting a deal even if it needed a CLA. After reviewing the test roll, I checked further and it appears that at 125 and 250, the second curtain is catching up to the first and only exposing 1/3 of the frame. At 500 and 1000, the curtains are together with no separation. You may be having the same issue. Let us know if the pics below represent what you're experiencing, too. I sent a PM to Eric Hendrickson (EricTn) about having him service the camera, you may want to do the same. I am absolutely in love with this camera, so hopefully Eric can work his magic on it.