Hi David,
First off sorry for the delay. I was traveling to/ at the Thailand Heli Blowout in these days.
The Engine mounting slots being slotted has been tested and proven and doesn't cause any problems to the functionality of the model. Additionally since carbon isn't a 100% rigid material the lower carbon plate arching slightly has proven to not cause any issues. This is actually more caused by the fact that the bottom of the engine mount is machined at 0 deg angle, and the bottom of the frame is at a 2 deg angle. This was done by our machinist to save a lot of time and money for machining on a 3 axis mill rather then 4 axis. It's exacerbated slightly by the engine mounting having to have been lowered, but still has proven in my testing to be a non issue. Really once you bolt it all up you'll never notice it or have a problem.
For these 2 things, (the engine mounts in the frames having to be slotted, and the bottom plate arching slightly), Mikado, with my approval, has not deemed them as items that effect function or performance of the model in any way. So they see no obligation to replace the frames. We of course will work to improve the next batch of kits, but there is always 1st production run jitters that have to be adjusted for.
That being said, if your engine mounting slots are cut excessively poorly and with excess slop then that is something that can be looked at by Mikado service department. Same process like with any other issue a kit might have. They would need pictures showing the slots, maybe also with a caliper measuring the width of the slot etc and then email them to
service@mikado-heli.de
Hope we can get the issue sorted and resolved and get you flying it soon!
Kyle