I replaced the water pump but can't get the belt adjuster in place with the belt on, broke one adjuster with too much torque to get it back into slot. I have a diagram of the serpentine belt and I've got that on correctly.
How do I get this belt adjuster back in place into the slot?
Help.

You bolt up the tensioner first and then take a 1/2" drive ratchet and rotate the tensioner until you can put the belt on. It's usually easiest to put it on one of the idlers last.

I have the belt in place but the tensioner won't go into the slot. The tensioner is bolted on and loose but I can't get it into the slot. I must have the belt on wrong or something because I just can't get the tensioner over far enough to go into the slot with the belt on.
Any other suggestions?

huh?...take the belt off...bolt up the tensioner...route your belt,leaving it off of 1 easy to get to pulley...then put a breaker in the hole of the tensioner and cam it back...then loop the belt on the 1 pulley and then release the tensioner

In the past on my Tahoe I loosened the idler pulley so it gave some play, with the tensioner all the way in, I was then able to slide the belt on there last, then tighten it back up. Don't take the tensioner bolt all the way out, just enough to let it drop down some.

I noticed today that the tensioner has one square knob and one round one. Maybe you got it upside down???? You don't have to loosen the tensioner or remove it to change the water pump.