2013 Jumpy sticky steering servo. Getting better when warmed up...

[Axa]

Any ideas what causes this problem? When starting up the servo is hardly working at all at least turning right. Fluid level is ok. After short drive it improves successively but keeps being "notchy" turning right from center. If going slow and keep turning quickly between full left and right it disappears. Then back again next startup. Any ideas? Could it be a piece of rubber that blocks a valve or something?