Could anyone tell me a reasonable price tp pay to have a cat pump (4.6 Gpm) rebuilt? the casing and all seem to be in good shape,also could the unloader valve cause pump to go bad. I only have 800 or so hours on machine and I thought Cat was the best. Ive never had a problem with cavitation,and take care of servicing it just like its my living,,cause it is. Thanks in advance for your time and advise!!