serpentine belt tensioner assembly

I am replacing the belt tensioner on my 98 Jimmy. How do you install it so that it applies the proper tension to the belt?

Installed the new belt tensioner. Went very easy. Undo center bolt, pry off old tensioner. Move belt slightly out of way of tensioner pulley, align up center bolt with its hole and align the small guidepin on back of tensioner with its hole, tighten up the bolt. Carefully force the tensioner pulley down at the same time sliding the belt into position over the pulley grooves, Check belt grooves are aligned. Done!

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