Good advice on the Muffler Expander .....
Our spar pins were VERY stubborn going in. This is what we suggest....
1. Grind down/smooth the ridge on the end of the pins to make it more of a bullet shape.
2. Grease the pins liberally using lithium grease or similar.
3. Insert the muffler expander in one spar hole and use a socket wrench to expand the radius of the muffler expander. That will produce a PERFECT alignment on that side.
4. Now move the wing tips up and down to bring the opposite bushings into alignment (feel the inside with your fingers).
5. Fabricate a shim and wedge it between the spars and the white plastic block in order to bring it into alignment. Ours required a .064 shim.
6. Twist and turn your greased pin into the bushing hole, tapping it with a plastic tipped mallet to until the pin is in place. It gets easier each time.
7. Remove the muffler expander..... and twist/turn/tap the pin into place on that side. Wear shop gloves so you don't slice your hands on the sides.
After inserting/removing the pins a few dozen times, it actually become easy. We use a banquet table with the legs sitting on Harbor Freight moving casters to support a wing when removing it from the fuselage. We fit two RV-12s in one T-hangar.... That requires one wing to be removed from one airplane. Easy enough to do with one person.
I hope this helps.....