Are you saying that when you track the blade it stays centered on the upper wheel but comes off the lower drive wheel?

Does this saw have bearings that run against the back of the blade? If so, move them away from the back of the blade at upper and lower points. Unplug the saw and turn the wheel by hand and adjust the tracking at the upper wheel. If it appears to track plug it back on and "bump" the power on for a second at a time and see if it will track. If it tracks ok put the bearings just touching or a papers thickness behind when it is running free and not cutting something.

If this doesn't work:
Is the lower drive wheel rubber crowned (curved) or flat ?

If you put a straight edge on the lower wheels' 2 outside edges, does it line up with the upper wheel? The 2 wheels should line up. It's possible that the drive wheel needs repositioning.