I have two timing lights, the first is an older chrome sears light with no features , but always seems to work. The second I a fairly expensive snap on MT-2261A timing light I bought a few years back as it has a built in tachometer and can be dialed forward or back with a digital reading. The bad part with the snap on is on late it seems to work at intermediate times. It almost like it stops picking up as the tach will fall of and the flash slows down. For the money it cost it for sure should not give any issue. I wish I knew how or who to repair it as it has good features.
Matt