Belt screaming could mean you need a new belt. But it does look ok from the pic. Hard to tell.
Does look like the belt is near the edge of the tensioner.
Whats very easy to do. To check. Find a socket that fits over the nut of the tensioner pulley.
Do you have a long socket wrench ? If not use a hollow bar over the wrench handle.
Im surprised your mechanic didnt show you this. It only takes a sec....
Apply pressure so as to move the pulley away from the belt. You can then remove the belt from that pulley.
Be careful so as to place the belt in position to remember how it came off. Dont remove the whole belt from everything. Gently remove it from the one whilst watching and recalling its original path around the others.
Now you can check the bearings on all the pulleys. Spin the tensioner pulley. Feel it, wiggle it to see if it has any play. If it has up down, left right play, then the bearing is shot. You buy a new pulley.
The chances that you need a whole new spring system are kinda between slim and nil, And slim is outta town LOL.
You dont even really have to remove the belt from anything. Just use the socket wrench to release the tension. And you can feel the pulleys that way.
As long as your not leaking coolant then chances are your coolant pump/pulley is fine. If it squeals while turning then it may be your power steering pump.
Be aware though. If it is your tensioner and when or if you replace it. There is a chance that your coolant pump may begin to leak. The extra pressure could cause that.