My keel lifting mechanism is working fine but it is over 5 years now since I bought my boat.
Should I change the ropes for the lifting mechanism before any failure?
You should at least take a look inside the centreboard case, for wear of the ropes, (especially where the main rope comes out of the centreboard head) and for checking the position of the stopper knot in the pulley rope which limits the "full down" position of the centreboard. If your boat has a leeward tendency, that knot position is very likely part of the cause.
