bobcat t 250 low oil pressure shutdown

[ficus]

I had the engine rebuilt just finished installing and am having engine shutdown to low oil pressure . replaced oil pressure switch and same condition. put a mechanical gauge on and have 56 lbs cold and 30 lbs after its warmed up. The oil pres switch is disconnected from 3 wire connector. Does any one know what to check on I haven't found much info in the shop manual. Thank You

 

[1fastmofo]

Make sure drive belt on hydraulic pump isn't loose

 

[ficus]

Make sure drive belt on hydraulic pump isn't loose

I installed new bobcat belt and tightened the spring tight and slid the holder according to manual. could I missed something? is there a sequence to testing the sensors that comprise the shutdown circuit? the electrical diagrams seem rather vague. any help is greatly appreciated