In your printed sleds, does the sled hold the battery on an angle to give it some initial tilt? looks like it from the diagrams.
Yes, it is at a slight angle, probably to expose the end for when you solder a wire to it. Photo attached, shows how far the printed sled goes in before it jams. Probably just needs a small amount of material to be filed off for it to go in all the way.
Got lots of resistors from China already, waiting for the main components...
**UPDATE**
This tip just in from Sam from the iSpindle project - try this before you take a Dremel to your sled and shred it:
...But here is the trick, put the sled into hot water ~140°F where it gets soft, then push it gently into the sled. Repeat it if necessary, you will squeeze it until it fits. Not perfect but works!
** UPDATE x2 **
I actually tried it, put water in a ceramic dish, floated the sled on the water and put it in the microwave on the beverage setting and it worked well to soften up the material so it could fit the tube, however the sled legs splayed out a little (warped) so flipped it over and pressed it back into shape and that seems to have fixed that issue. I'll find out when I get the circuit board but shouldn't be too difficult to reform it.