I'm not familiar with the filler you're suggesting.

I'd be very tempted to trim the edges back by the thickness of the wood, then glue square stock back on where the problem exists (I suspect it's just on the end-grain).  It'll clean up your problem, and strengthen the thing against warps, too.

Whatever filler you use, make sure it's about as strong as the wood when it's dry -- there's some filler out there that dries up to be almost nothing.  It's nice and light, but not exactly structurally sound.

Rob, I've had that problem before and the easiest thing for me was to make a new piece. The other suggestions work just as well, but if you have the spare wood cutting a new piece on your scroll saw does the job.

I like to cap the tips of my solid surfaces with grain running chordwise even if I'm not trying to salvage poorly die-crunched wood.  If I could do that and salvage the die cutting that's what I'd do.

Of course, you always have to use your judgment about whether you should pitch a part and redo.

The model lite that I used did not like dope, it melted. Then it would hard but did not keep it shape, or stay flat. It was some from Hobico.

Steve