HI
This plantations patterns tilt umbrella seems to have lost the tilt button and any connected spring or screw.

Could someone please explain how the mechanism works and how I can fix the umbrella. Ideally I can use parts from a hardware store.

Many thanks

Pics here
http://postimg.org/image/og1l5g733/

http://postimg.org/image/hqzn36b4v/