"Quarter" is your problem. All drivers must have crankpins at the same angle - usually 90 degrees or thereabouts.
Pull the rods off, set one side at top or bottom dead center, and make sure the other side is in a very straight line - in line with the axle centerlines. A loose driver can be fixed at this point with Loctite and your special screwdriver.
To hold the drivers at top/bottom dead center, you can drill an aluminum plate with tight-fitting holes - spacing must be exactly the same as axle spacing. If the rods are tight (unlikely) they can be used.
Then the rods must be re-fitted after the Loctite sets. You fit them at front and back dead center. You will see interference if there is any - the rod must be adjusted so there is no resistance. Use a magnifying glass, and pins without caps. You may have to make test pins.
