Does the Inca have flat tires?
What sort of blade do you have, as in are you cutting tenons with a very narrow blade.
It could possibly be set up that way to work for a wider blade.
I don't have first hand experience with the Inca, but on my large machine which has flat tires, I set it to 90 with good tension on a suitable blade for my machine and track the blade so the teeth overhang the edge of the tire,
and align perfectly then.
As in, it will arrive at 90 degrees once the blade is tensioned for cutting tenons.
If your using a narrow blade then you will track on a different area on the wheels, and may have to keep an eye on things (long term)
presumably more so the wider the set is, on your blades.
I would be unsure of what the max blade width on that machine, as many brands have rather optimistic opinions on what that is, so I'm not telling you to put a honking big blade on the machine.
Sorry if im preaching to the crowd, but worth mentioning.
It could be the case that a previous owner wanted more capacity on the saw
and removed some shims or nuts for adjustment, if they did that I don't know.
Could be someone lost/misplaced them during transportation or renovation either.
Nothings ugly bout few shims.
It's when you do something irreversible is when that happens.
All the best
Tom