power steering

[Vitalie]

Well the steering wheel is sometimes to hard to turn stopped. It is abrupt like it turns a bit easy and then hard for a little then easy again and hard after. There is a squiking sound when it gets harder.
No leaks. The level is proper. I cleaned the bottle and the filter. Changed the fluid there. But the problem is intermittent and only when stoped. Driving is fine.

All the advise appreciated.
Thanks