Idler pulley alignment

[bertsmobile1]

If that is the 54" deck with a single belt part No # 1725208SM then it is indeed a double sided belt and all pulleys are V pulleys.
Does this look like what we are playing with
View attachment legacy_xl_2927.pdf

 

[bertsmobile1]

https://youtu.be/is7llxoGTPI

I really wish you could learn how to take a diagnostic video.
Rule No 1 PUT THE BLOODY CAMERA ON SOMETHING SOLID & STILL.

2) FILM SQUARE ON ALONG THE BELT NOT AT AN OBTIUSE ANGLE so we can actually see the malalignment.
The video was a complete waste of time looking at and effort taking.

Under the idler is a spacer.
The only difference between dozens of identical pulleys is the height of the said same spacer, in your case part # 11 in the diagram I posted previously.
If the pulley is as you say 5/8" out of alignment in the vertical scale, which to date none of your images have illustrated then there is a better than average chance the wrong pulley has been fitted.

Now if you really want to illustrate what is going on, put the camera on a brick so it is at the same height as the belt and slightly back from the end spindle so we are looking along the belt.
Then remove the belt and take the same photo again.
Either the pulley has the wrong spacer or the tensioning arm is in the wrong place.

 

[eklevens]

Yes that is what Im playing with.
Ill try and take a better video.

 

[eklevens]

Here is the best I could get. The belt gets in the way of getting a good angle from the end spindle.

 

[Rivets]

Bert has the correct model parts breakdown and that model does use a double V-belt, so I am wrong, all pulleys should be V pulleys. My suggestion is to remove the tension spring and see if the idler arm moves freely and the pulleys stays flat. I’ve seen idlers that are not at the same level as the spindle pulleys. Check to see if someone has changed the idler pulley and you have two spacers instead of one, between the pulley and idler arm. Check Bert’s diagram.

 

[bertsmobile1]

Yes that is what Im playing with.
Ill try and take a better video.

Thank you that is so much better.
Remember you have the real mower in front of you seen in 3D but we just have a 2D image on a flat screen to work with.
Pull the tension arm off and check where the spacer part No # 5 in the diagram is.
If it was replaced under the arm and not on top as per the diagram that would push the pulley way too high
Could not find your pulley number listed in my after market catalogue so I do not know what the stand off height of the pulley spacer should be.
If some of the other techs have access to better information they might be able to confirm if it is correct.
Not uncommon to get a customer having belt problems because they bought the cheapest 6" B section V lawn mower idler off ebay but failed to swap over the spacers.