Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I have a Mamod Challenger also. Mine is one of the early ones with the stainless-steel piston/rod and squared cylinder. It does have a slight bulge in the boiler barrel, I think that's where the end cap is. It doesn't have the problems yours is experiencing, but a word of warning about the gas tank. I bought the gas scuttle also and this tank as well as the one on the SP8 I have leaked gas out of the stem (and lit up!). Both have been replaced with BIX tanks. BIX tank threads are not compatible with Mamod pipework, so that had to be changed too.

Due to these glaring oversights by Mamod, I'll never buy another one.

I checked mine out also, just like Bret's. Slight bulge, stainless or nickel rod. A very small wobble,
square cylinder too. Good rivet's. It sounds like they cheapened them up. Mine was built in 2007.
Maybe they had a big turnover of employees due to the pandemic like a lot of companies experienced.
It looks like a practice one or a dropped and returned one. I hope they square up with you.

They’ve offered to send a newly machined flywheel on Monday…

Here’s their answers to the other questions 

[ Guests cannot view attachments ]

I get a kick out of their excuse, and that's all it is. In all of our engines, TR, TE, and showman's,
we use silver solder that is hotter and it shows the bulge blah, blah, blah. Mine doesn't have that
bulge on the other side, they all seam to be on the left side, blah, blah, blah. This has been going
on for decades, you think they would have gotten it fixed. I don't see these problems with Wilesco.
I see a lot nicer and more authentic detailing in the Wilesco line too. My Mamods are two Minors, one
WS1 (Workshop), one SE3, and one Centurion, all bought used. I would never buy anything new from them
now, not just because of the lack of quality but because of the lack of aesthetics. I'm done with Mamod.