It's been years since I've sold Myers, but the SRM4 was a Pump that I sold a lot of. I still have one in use at my home. The Float was separate from the Pump with the Piggyback Plug. You can buy a new Piggyback Float and replace the old one once the pump is out of the pit. I used to have several in stock, but have since gone to a 3 wire float for different uses.
Any Piggyback 13 amp float you can find will work, just make sure it's a pump down not pump up.