Its not uncommon for the stock extruder to get hairline cracks and fail over time. You can either reprint another stock extruder setup and also run the risk of the less-than-common bowden tube fitting break, or go all metal and avoid both issues happening again in the future.

This is the exact one I'm running now - https://www.amazon.com/dp/B01LO3HKK4/ref=cm\_sw\_em\_r\_mt\_dp\_U\_kjSwEbVY38V85

Don't forget to also grab a MR104ZZ bearing as well; it will allow you to keep your stock gear on the stepper motor (no need to recalibrate the extruder rate).

Good instructions I followed here: https://hackaday.io/project/28433-monoprice-select-mini-painless-extruder-upgrade