Am I Missing Something? Sentry AI Sinking Into Earth(Code Added)

So I'm making a sentry AI that moves from point A to point B but the problem is when I hit it with a slow it starts to sink below the baseplate. But strangely increasing the model size causes it to sink less but I don't know why.

Is there any way to prevent this sinking without having to set a min speed (since I don't want to increase its speed just to make the current a min speed) or changing the model size(since I don't want it to be so large that it interacts with the map strangely)

Or if there's another alternative to rocket propulsion(Model just goes from point to point in a strait line(CanCollide is set to false since I don't want player to interrupt its path))

I'm not asking for a script or anything I got that just an alternative or maybe a feature on rocket propulsion i'm missing that someone could point out, this has had me puzzled for a few days and now's starting to get annoying.

People have asked for the script don't think it'll help much but here:

local RP = Instance.new("RocketPropulsion")  
RP.Parent = Sentry.HumanoidRootPart
RP.Name = "mover"           
RP.MaxSpeed = game.Lighting.SentryLevels
:FindFirstChild(Sentry.HumanoidRootPart.Level.Value).Speed.Value / 10 (lowest speed is 6.5 highest speed is 25)

Upon reaching points the target is switched to the next point but I don't think that's relevant since it'd need to successfully make it there first.