The TCS chiller pump has been rebuilt and should be ready to act as a back-up now. In the future if the water pump needs to be rebuilt it uses a a type 21 shaft seal, 5/8" shaft size, 1 1/4" seat bore. The replacement o-rings are 4x dash number 012 and 1x dash number 242. It also uses a standard external retaining ring with a 5/8" OD. Use a light grease to seat the shaft seal, or else the rubber will tear (voice of experience here, oops).
The chiller is currently running in a small closed loop to see if any leaks develop overnight, it is on the mezzanine with its other siblings.
The rebuild survived a week of recirculating, so it is now drained and sitting at standby waiting for the day it is needed again.