They're a tight fit. I didn't like the idea of banging on the pushrod insert. So I bought a pair of threaded rods and angle irons. Drilled 3 holes in the angles, the middle for the pushrod and the others for the hardware store threaded rods. I then used nuts and washers on the hardware store rods to apply pressure to the pushrod insert, similar to an arbor press I suppose, while a heat gun was applied to the tube.
Ann Arbor, MI
RV-9A under construction (wings)