I do not think you are harming your cylinder.
if it IS leaking I would get it fixed, if their is a crack I would hate to see it break under pressure...
also, I would think normaly a certified welder would weld something like this as it is a pressure vessel of sorts..
personaly, if it was mine I would pressure wash the entire thing at the car wash with plenty of soap and make sure it is a weld thats leaking, and exactly where, i doubt it is a weld, but maybe a plug or a fitting that is leaking
if it IS leaking from a weld, and your cheep dont skimp on on the repairs. If you do it yourself, take the front end apart, slide the shaft and seal out, wash it out, grind out ALL of the crack clean everything and lay down a pretty bead with good penetration, make sure your start and stop areas are GOOD... then clean out again, check seals and reinstall.
just my 0.02 cents
-Leo-