If the sail is on lugs, hoist it a bit and see if the lugs can "wobble" in the track, they could be worn.
Also try squirting dish soap on the lugs and in the track before you hoist. My main is old and tired and I've been using this trick for a while.
You can buy fancy "sailing" lug lube but it's not worth it.
OTOH - you could have a frozen sheave at the mast
top - unhook the halyard
, attach a tailing line and hoist the halyard
without sail but with some "tension". It should run smooth.
Oh - Also hoisting when not head
can also be problematic as the lugs are canted sideways.