This might come across as a backhanded compliment, and this pertains to a Premier locomotive, not RK Rugged Rails, but I've had so many complaints about MTH products that when something good happens, I think it's important to post that too ...
I've experienced so very many frustrating events with all our MTH stuff. Our experience has been that these locos are so fragile that any little thing means a trip to back to MTH for a repair. Around Hallowe'en, we overfilled one of our Premier Mohawks with smoke fluid and - no more smoke from the stack. Instead, smoke just kept pouring out from under the boiler sides. In all honesty, I really liked the "steam chest" effect. I probably ran it more with this smoke effect than ever before.
I turned it upside down. No luck. I let it sit for two weeks and then ran it some more. Same beautiful steam chest effect, no stack smoke. Another week upside down - no improvement. Finally brought it to two different repair guys. Both said the smoke unit was ruined. Also said my electronics were likely fried and it would be pricey to fix. Well, I'm tired of putting money into these MTH locos so decided this would just be a Guinea pig for my "fix it" and weathering skills.
Finally decided tonight to let this thing run for a long, long spell, and then maybe the unit would get real hot, dry out and come back to life - or if not, EF it, the thing could just go up in flames. Well, it was running for maybe 45 minutes at a nice constant 25 smph and all of a sudden, the stack started to pump out wisps, then thicker wisps, then eventually nice full plumes of smoke! Darn thing is pretty rugged after all! Just needed some tough love.
Peter