Hi guys

I finished my 3" Burrell (to HR Plastow's design) in 2012 but I've been having problems with the pole reverser and the valve gear.

The problem is that when the crank is at its highest point, I can't push the reverser forwards or backwards. This is partially the same when the crank is at its lowest but I can move the reverser with a bit of effort- something I know shouldn't happen.

Is this because the expansion link isn't true in some way? Or there's a problem with the slide valve, weighshaft, crank alignment or eccentrics?

I found that there are a lot of imperfections on the drawings for this particular engine so is it possible that I have made something to an incorrect/improper dimension?

Is there anyone who has built this kind of engine experienced this before or avoided it in some way? Is there anyone who might know what the problem might be and know how I can resolve it?

Many thanks

Dan