Hiya, I don't own a Stuart, but until some one who does lets you know, I think you can relax about flow. Making a mistake should only affect the way the switch reads i.e. off becomes on etc. If you do pop them back on the wrong way round it shouldn't do any harm as the switch is in line. If you are worried get a Multi Tester on Ebay @£5 or £6. I have included photos of my Tri Pact Speed Controller in my 1:12 M1A2 MBT. You may consider one if your original set-up ever blows. I love "conversions" and your Stuart must be a dream with all that access to 1:6 stuff. I use Plan b toys 1:12 action figures, please check out my Gallery, but due to the lack of 1:12 stuff I end up making a lot of it by hand.