Hi Barb. I would take the belt off along with the top of the filter. I would remove the o-ring and inspect it for damage. If damaged or deteriorated, I'd replace it, if not clean it and lube it using a silicon type lubricant, nothing petroleum based. I would then clean off the top and bottom parts of the filter that mate together, using a hose then a soft cloth. Then re install the o-ring, and reassemble the filter. As you are tightening the belt, make sure to frequently check if it is seating evenly. So tighten the bolt one or two turns, check the belt, tap it lightly with a rubber mallet, then tighten the bolt again. Repeat this process, making sure the belt is seated evenly, the o-ring is clean and lubed, and the bolt is tight. I've had to loosen and readjust my belt a couple of times in the past until I got it right.

Tom