Thats for the heads up. what size is the main block?

My friend has the little denford one and said it suffers from similar issues. We were looking to make one with the pnuematic actuator but seem like a lot of work to me.

I just seen this one http://lukesprojects.weebly.com/auto...l-changer.html it uses two adjustable pawls and looks quite substantial

Do you know if the pneumatic ones are the best option? either way it will be an investment so we want to make the best possible version