Was replacing a belt on my davinci and found the real problem… The y rod bearing holder was in pieces. Good thing I have a 2nd printer to make some parts… It still amazes me that we can do this. As for the davinci… MAKE CIRCLES GREAT AGAIN!
Step one get printer working
Step two re-print the parts so you have a spare.
It’s now working… Better than before. Glad I have 2 printers. One can repair the other!
TOTALLY CALLED IT!! 
@ThantiK all of them seem fine until you take it off… Still a flat side in circles but that’s x axis. Anyone know the paper clip belt tensioner trick?
I absolutely went through this exact same scenario! I was mortified. When I had the hubris to look at my first printer, a DaVinci 1.0, and decided to hack it and rebuild it, I realized how important those little things were and when mine cracked just like yours did, I was pretty mad. I fixed the situation with pliable plastic pellets I found at Radio Shack, so this was a couple of years ago, that when you used boiling water, turned it clear, pliable, moldable, and when it set, it was hard as a rock. I used the broken pieces to essentially make a mold with the hot plastic, let it set, used corn starch over the new mold, and did the process again to create the next best thing - that part is still around and takes plenty of abuse - you can find the plastic here - https://www.adafruit.com/products/2504?gclid=CjwKEAjwubK4BRC1xczKrZyj3mkSJAC6ntgr0CtzYyr0RjgoEHgPQinkDrLYYdEyf8G6IddAD0co1BoCeWvw_wcB