Help!!! Rhino Scrum machine

Looking for some help please. Tried to adjust the height of our scrum machine last night but couldn't figure it out. There are windy handles to adjust the height of the pads but they seem to be locked in place. I figure there must be a locking pin or something but can't find it. Any ideas? Thanks

Hmmm, on their website they sell a "Front Locking Pin & Chain" if that gives you any clues? And "pad-height adjustors" http://www.rhinorugby.com/store/pad-height-adjusters-P.html.

Which Rhino machine is it? http://www.rhinorugby.com/store/scrum-machines-C.html?p=1

Cheers KIWI. Can see our machine alright but no details on adjustments. I was hoping someone here might have first hand experience.