One motor I have found to be reliable and at $200 very good value they are the DMC 6.5 hp motors. I have fitted several to the Deutscher 22 inch slashers and never had a problem. Only issue I think with fitting them to a standard mower base is that they may be a bit heavy and they have a 25mm shaft so you would end up with a boss problem. This would be such a massive improvement over buying one of these $1000 pieces of Briggs garbage. Weight is my only concern
Yes, I suspect it is a bit of a rip off and other catchers will fit. There are "universal" ones on ebay, but it is hard to tell if they will fit or not. Possibly all made in the same factory in China. We often pay a lot more simply because a brand name has been stamped on it.
At a pinch, I suspect 40mm medicine bottle caps - like the ones on vitamin tablet bottles - could be used. They fit over the rear bearing on modern EasyRoll wheels and will also fit the slot on the back of those 1980s-90s silvery plastic Rover wheels. They are too wide of course, but can easily be cut back to the 7mm. Then drill a hole in the centre.
Rather than type it all out myself, these are the general causes of surging and hunting (which is what it sounds like your mower is doing) as copy pasted from google.
Common Causes and Solutions Blocked Carburetor Jet: The most common cause is a clogged carburetor, particularly the tiny pilot jet restricting fuel flow. Clean the carburetor, specifically the bowl nut and its jet, which are often to blame. Stale Fuel or Water: Fuel that has sat for too long can cause blockage, or water in the fuel tank can create erratic running. Failed Diaphragm: On some engines (especially older Briggs & Stratton), the carburetor diaphragm can harden or rip, causing air leaks and poor fuel flow. Air Leaks: A faulty or torn gasket between the carburetor and the engine intake can allow too much air, forcing the engine to hunt for a consistent RPM. Governor Spring Issue: A worn, damaged, or stretched carburetor spring can cause the governor to fail to stabilize the engine speed.
In my experience it usually either a dirty carb or a faulty or misconfigured spring (either throttle or governor).
This guy does some good videos on fixing mower issues.
If the above video doesn't help, look through his other videos you might find something useful.
Hi Geoff, Sorry for not responding sooner. Ive been off the post for a while. The restoration has come to a standstill as the catcher is the last part. Thanks for the drawings, ill be able to use the old catcher for the catcher hooks. Thanks again, Chris
I eventually got the right pulley only to find it had a small piece cracked out of one of the pulleys. Probably repairable, but I couldn't be bothered. I have since sold the Cox ride on, considering it too much trouble. I am not really into doing up secondhand ride on mowers if truth be told. They are just too heavy for me and my back gives out. I still have the dual pulley here if anyone ever needs one. An engineer should be able to repair the broken out bit.