Hi folk,my first post please help. After rebuilding the gearbox to rectify the 5th gear problem. I have no oil pressure. I have been very carefull with this bike and never had a problem before. If i crank the engine by hand oil pumps slowly out,but not enough to fill the filter housing and up the oil tube to the head. I have checked photos of the rebuild and all o rings and dowls are in place. The engine/oil was very clean inside so i never disturbed the oil pump. Whats going on!!