Raw water pump frozen

This raw water pump will not turn, and I can’t remove it. I don’t know how long it has been since the engine has been run, at least 14 months, possibly much more. The cover screws won’t turn, I didn’t put maximum torque on it because I didn’t want to break the brass screws. I removed the support(?) angle bracket, but the pump body will not move even a little bit. It looks as if the pump is driven through lugs and it appears that it may not actually be designed to be bolted to the pulley, but I’m not sure, the illustration of the pump doesn’t show lugs. The angle bracket appears to be intended to prevent the body of the pump from rotating.
This is a Ford FSD425 marinized with a Lancing Marine kit. The pump (I think) is a Jabsco 29440-1001. Something is totally seized up, perhaps both the impeller and the bearings.
Any suggestions?

The impeller is rubber, so if it was bonded to the housing, the vanes would tear off and allow the pump to turn. Most likely cause is frozen bearings. The pump has to be disassembled. Not too hard to do. I rebuild my pumps. The pulley may need to be pressed off. To break loose the brass screws use a large flat tip screw driver, put it in the slot and hit the end of the handle. If you have help, try to turn the screw driver with channel lock pliers while someone hits the end of the screw driver with a hammer. Soaking the pump in hot water may help. There are probably YouTube videos on rebuilding a raw water pump.
This is probably not the original raw water pump. What I have on Jabsco 29440-1001 is it's a crankshaft mounted pump. A bearing supply should be able to match the bearing and seal for about 1/2 of what a marine dealer would charge.
For more info try Depco Pump Co: http://www.depcopump.com

I'd bet on the bearing being frozen...which means the pump will have to be removed to be rebuilt.

heating up the housing will help to free the cover screws.....and a hand held impact driver with the correct bit should pop them....maybe replace them with hex heads for the next service event....

2X on the bearings being readily available from the supply house....