Seems like a very good quality and good looking steam plant there Jim!
Sort of distantly reminiscent of the Cheddar Westbury plant in some ways.
The difference in power and speed between forward and reverse suggests that the timing of the valve linkage eccentrics might be out of best position by a few degrees, or some similar minor issue.
To change the timing Daniel would be problematic. To make it an easy DIY construction the axle is flattened on where the grubscrews will go, not an impossible thing to muck around with but job number 101.
I was surprised on the load that little bulb put on the genny.