I want to repair our cast iron rjs-50 red lion shallow well jet pump. Serial no. 2597, meaning 25th week of 1997 I learned. Motor would run but it doesn't deliver or move prime water. I took off the four bolts and with a fair bit of pulling split the motor from the pump casing. Now, however, I can't figure out how to get into the casing to check impeller. Apparently the shaft was at least partly unscrewed already, and this allowed me to pull casing / impeller compartment from the motor. But I can't figure out how to open the seal plate -- seems tightly pressed without any entry mechanism. I'll attach photos.