Shimano Vanford spool stopping

[phishxxii]

A friend gave me his Shimano Vanford 2500 to fix .It seems when reeling the spool goes up and down but then stops ;then continues going up and down.I checked the internals and all the gears(main and crosswind) looked fine.There are other gears that turn a worm gear and they look good also.What could be making this malfunction happen?

[Gfish]

It comes to a complete stop against the crank force? Or just a pause as the crank rotation continues?

[JasonGotaProblem]

Which specific model?

[Swami805]

Vanford 2500, I have one, nice reel for the $,very light and incredibly smooth. There's got to be something slipping to be intermittent like that