I'm building my MkIV Male as motorised. As far as I can see the roof section (upper hull part D7) is supposed to be left removable.

Unfortunately there seems to be a bit of a problem with this as this seems to mean that the unditching beams parts D3, D17 and the rear parts D32 and D31 can't be permanently glued to the main unditching beams (parts D1 and D21) or if they're stuck to the main unditching beams then the smaller front and rear parts of the unditching beams can't be glued permanently to parts C1 and C2. Anyone else had a problem with this?

You put your finger on it! I used Gator Grip glue to attach those end pieces, but I also do not expect to take the lid off anytime soon. I think Mr T just can't bring himself to stop offering those openable hulls...

I wonder if it's necessary to have the top hull opening if you're doing it as motorised seeing as the side sponsons can be removed? I'm not sure what to do with it.

I built the Tamiya Mk IV and glued everything together except the sponsons. I glued the unditching rails together and sanded the seam smooth then glued them on permanently to the hull. You can get at the battery just fine by pulling off either or both sponsons.

The only reason for leaving the top loose is if you ever need to get at the electric motor/gearbox. I doubt I'll ever want to, but who knows? Maybe the two-motor radio-control parts will pop up somewhere, enabling me to steer the tank?... (Hint, Hint, Mr T)

Maybe I'll probably just stick it then.............or I might try sticking the unditching beams together and seeing if they'll clip into position on the front and rear (probably not though).