I made some progress last night, putting in about 2 hours.
Here's the kit out of the box with just the wings separated from the sheet.
Scraping down the leading and trailing edges with my trusty X-Acto blade.
Dry-fitting the wings together - a perfect fit and razor-sharp trailing edges. It has wings! You can also see my hi-tech sanding block made from a scrap of plywood.
Then came the Oh S**t! moment. MPM messed up the shape of the wing, at least compared to their own drawings in the instruction sheet. The left wing, and only the left wing, is swept back too much. The right wing is perfect - go figure. It looks like I will have to razorsaw the left wing at the root, align the wing properly, glue some styrene behind the joint, fill the gap, and rescribe the panel lines.
I will wait on that until I receive the MBI book on the Avia 35/135 that I ordered from Aerobooks. Maybe MPM's drawing is wrong.