From what I understand / believe I would assume a bias could only develop due to dealer interaction with a wheel (outside of extremely rare factory mishaps). The slot roulette has a large plastic enclosure protecting it from any outside interaction, but I asked a tech walking the floor if they perform regular balances for the wheels and he said they never have and don't intend to. Would be interested to know if anyone could chime in!
If you're looking for a bias, it might be helpful to know either when the machine was installed (more or less), or when the bearing was last replaced.
I know some places out here in the sticks replaced their Roulette Evolution machines (with failing or failed bearings) with Interblock machines with that football side bet a bit under 2 years ago. Not sure what the service interval on the bearings is, but I'm reasonably sure that they don't go bad immediately.
Those machines also often display the results of the last 100 (500?) spins, in case you are trying to spot a bias. 100 spins is not enough to clearly identify a bias; if you were looking for one, you would need to make several visits over the course of several days to snag a clear picture that a certain number or group of numbers is hitting less often than others.
I have seen two different type of these. One by Alfa Street and newer ones by Interblock. I don't know about bias. As someone mentioned I'm sure the computer checks for that. What I would do is see if there is a bias is with clocking the wheel. The Alfa Street ones launch the ball out and actually increase the speed in the first few seconds, presumably from air jets inside pushing the ball. The Interblock ones just launch the ball. I found this one that pretty consistently would take 23.75 seconds from launch to the time it would hit the first nook. From there it usually had very little splatter. I would watch it and a good 8 out 10 times it would hit almost in the same place. Unfortunately what I noticed is the wheel turns at different speeds. One spin it would be one speed and the next it would be a half second faster. It also sometimes spins at one speed and when the ball would shoot out, it would slow down or speed up. So not sure if these can be taken advantage of and I'm sure anybody who knows would not post on a public forum.