What a nightmare.
I purchased 1 that had been started from castings .it was a sod of a thing to get sorted but i did and it runs nice on steam .i had to finish machining no reversing gear
The only way I can afford stuarts is to buy some one else f....ps from TM and go from there
I would consider removing the inlet manifold so i can put air into either cylinder.
Then with sufficient air apply to one cylinder at a time to see if either one will work and go from there
Basically i would want to know if the left go forward then reverse
Then does the right go forward then reverse .
Once we have these four results we can go from there
Cheers
Dennis