Bijur lube pump issues...

Well I am cleaning up my new Bridgeport (J step head) It has the Bijur pump on it, I think its the L18 pump. It seems like it only gets about a 1/4" stroke. I cleaned the sump out as it had 1/2" of sludge in the bottom. I filled it with mineral spirits to try to flush out the crud in the system. It only moves the pump shaft a tiny bit which does not seem like it would move barely any fluid or make much pressure at this rate. Are these worth tearing down? or just replace the pump?

Thanks guys!