Ideas on what is causing my tilt wheel to tilt stiffly?

[Zurbo]

Recently the tilt wheel has become hard to tilt.
It's not wobbling or shaking side to side like the joint is broken or bearings that have fallen apart..
Just started doing it recently and has been working great up untill now.

Guess it's time to start ripping it apart, but I was curious if there is something common that I should be on the lookout for when I rip it apart.

Thanks!