I also think it is a good idea to go over how I assembled the dive planes and linkage.
The first thing to do is to thin out the inside walls off the dive plane area before assembling the model halves ( I know why are you just saying this now? Hey Im not perfect!) I did this part using a file and scraping the plasic away a little at a time, using the forward edge of the file. This will work but, its also very slow. The easiest way is to use a dremel and a round carbide cutting bit. It also will leave a better finish. The key is to no take to much off but just enough so you can get a control lever in there. Hold it up to the light to try and gauge you thickness. Also, having a finger behind the back I find assists.
Make sure you use your control arm as a gauge to figure out if you've taken enough away.
It is also a good idea to round down that edge so see in the picture a bit. This will give you a little more room to get a shorter swing arm in there.
When I was making the dive planes I wanted to make it so that the whole thing could be taken apart for repair. You just never know when your going to have to take her down to parade rest. To ensure this would be a possibility I used square brass as my rods when I molded the planes. This way I would only have to slide them through another square brass and I wouldn't have to worry about getting a set screw in there.
To make the dive plane control arm I took a piece of thin brass plate and drilled a hole in it large enough to pit a piece of brass square tubing that would slid over my dive planes control rod. After i got it in the hole i soldered it in and then trimmed the whole thing down to get the bare minimum required for operation. The bottom of the ting is defiantly at its minimum.