Turns out I’m short two 35mm spacers.
Coupler Problems. One was too small to accept a lead screw. Another had a small blockage not allowing a lead screw to insert all the way. I fixed both by the use of a cordless drill and some sand paper.
Inserting a washer between the coupler and the flanged bearing is not so intuitive. I removed the motor, inserted the washer and attached the coupler and then reinstalled the motor.
Tomorrow I’m off to the local hardware store. Wish me luck.