The 248mm booster was taller than the tallest practical print in the ender 3. It needs more like 220mm to be able to access the filament across the entire horizontal area. At 248mm, it can only print in the middle.

After much trimming of material, it burned its 1st stick. The extra detail & odor in this one made it easier to bear not having a full stack.  It's definitely more productive.

The launch mount definitely shows more of the business end than the doughnut did & is sturdy enough because of the right angle pylon alignment.  The pitch angle is slightly off.  It's not assertive enough to get a precise pitch angle.

Horizontal expansion in the thrust structure clamps & launch mount pylons is the trouble spot which needs most of the trimming.

The breach loading mechanism needs to have only 1 registration pin.  Having 2 makes it impossible to load.

The registration pin in the last one was almost completely worn down after 3 years.  The new one has so much interference from glue residue & .32mm layers, it might not be necessary.