Hello can anyone help with a problem with a V 92 6 cyl J E HALL ammonia compressor. I have low oil pressure about 15 psi and the unloaders will not load up. I changed the oil and cleaned the oil pump intake screen, did not help. I can manually operate the unloaders by forcing oil into port on bottem of unloader with hand oil pump but they will not load up on their own. Soleniods are working.