Parts Canada Zetor 8520

I have learned alot here but have placed very few posts. I own an 8145 just purchased an 8520. The glass on the left door ( 8520) needs to be replaced. First off I can tell you that Peter Laznicka at ZetorNA ( plaznicka@zetorna.ca) if you need info in North America contact him. OME.
Secondly Sean M. (sean@canadiantractorpartsdirect.com) he's a straight shooter and will give you a good run for your buck.
That being said, at the price of glass does anyone have pointers on replacing the glass on the 8520.? Also the button on the right mid cab that lookes like a 2 furrow plough with barbs.....what is that for?
Thanks for your time
Rick
Niagara Falls Ontario Canada

When you press that button it should lift the arms up and then when you press it off, arms will drop back to level they were before.

Thanks Vulcain 2. I need to get an operators manual...but that one truely had me stumped.

Rick