Hi! I just got a Minolta MD Macro 50mm f3.5 and i have a problem to solve with it. The lens looks so new not a scratch at all. It's a blue ring version. I heard that there are orange and white ring versions also. The focus ring gets tight when i turn it. Its not that tight but its hard to turn with one hand. What can i do to make focus ring work better ? Do you think that little oil would work ? Or avoid from oil ?