Hi Norm,
The mower looks like it's cutting well, I've found the caster wheels don't want to swivel well in certain circumstances unless
the turning shaft has bearings ,like a push bike or motor bike front forks.
I'd probably make a bracket first to lock the wheel straight and see how that goes as the wheel may just skid a little and not
effect anything.
From Wikipedia below
Trail or trailing
Caster angle and trail both influence the steering, albeit in different ways: caster tends to add damping, while trail adds "feel" and returnability.
The caster wheel on shopping carts are an extreme case – the system is undamped (unrestricted motion) but stable, as the wheel oscillates around the "correct" path. The construction has relatively high trail, but no caster, which allows changing of direction with minimal force.
In this case the lateral forces at the tire do not act at the center of the contact patch, but at a point behind the center. This distance is called the pneumatic trail and varies with speed, load, steer angle, surface, tire type, tire pressure and time. A good starting point for this is 30 mm behind the center of the contact patch.
I guess you could measure a shopping cart wheel to get the offset then upscale the offset to the wheel size you are using to get the best results.
I've also seen caster wheels change direction more easily when the pivot bearings are out in a wider path , like 2 flat plates at the top
of the wheel with the balls in between the 2 plates and with the bearing balls spaced out to a foot.
Cheers
Max.
