Just a tip of something I had to learn for myself. On a metal cutting bandsaw which twists the blade the procedure for installing the blade is often incomplete. No where have I found the missing bit of information, had to work it out for myself. Basically a band will track towards the "high point" of the band wheels. Metal saws usually have flat wheels with no high point in the middle unlike wood cutting vertical bandsaws. To ensure the blades don't tend to come off the pulleys the guide bearings have to be installed in this sequence.
1. with no guide bearing touching a blade that is running (by hand), true on the wheels, with back edge of blade correct on the wheels. slide the bearing that is nearest to the cutting teeth to just nearly touch (ie not touching with near nil clearance) the blade. Usually this will be the inside guide bearings. Lock guides in place.
2. Now bring the other set of guide bearings in to push the back of the blade over so it runs true to cut. eg work piece horizontal, blade between the two sets of guides vertical. Lock in place.
3, check tracking, if ok slide the rear support bearings to just touching,
The reason is that now the outside edge of the blade has more tension that the toothed side, so the blade will track to the non toothed edge on the pulleys. Because the blade will track towards the high spot of the pulleys and it now thinks the high spot is at the non toothed edge because that is where there is most tension.
Hope this helps.