Hi everyone I am looking for some advice on my MM 445 Utility. With the engine cold I have about 40 psi of oil pressure. After about 30 minutes of use the pressure falls off badly. About 5 psi at 1500 rpm. Less at idle speed. Changed the oil, used 30wt oil. Still the same. Adjusted the external screw on the oil pump, but it only changes the cold pressure and had no effect on the hot oil pressure. Double checked the pressure gauge with another one, and it is accurate. I am considering replacing the oil pump and see if it improves, but fear the problem really is worn out crankshaft or bearings. Is it worth the try to replace the bearings without removing the crank? Any ideas for me to try? Thanks!