yup, and this is why PLA for printer carriages is a bad idea..
You want ABS or PETg for them to withstand the temps long term.
As Kronikabuse said.. putting a cooling fan on the X motor is a very good idea.. it is undersized and tends to get hot, even when properly tuned. any standard 40mm, 12v fan will work using this bracket: https://www.thingiverse.com/thing:128526
He has already given you links for the carriages themselves - both to print your own, or purchase already printed ones. I highly recommend downloading and saving the carriage stls for future use.. things do break sometimes.
You will need to order linear bearings for them.. these are the ones I went with, so far, so good, and going on 5 yrs..
Easy RepRap - 12 LM8UU Linear Bearings
upgrading the smooth rods to hardened steel is highly recommended.. 2 pcs to do both X and Y.. cut with a bandsaw or angle grinder with a cut off wheel.. VXB Brand 8mm Shaft 30"
I have purchased that exact item a couple of times now for multiple printers - very happy with it.
any thing else we can help with, just ask!
SD4 #1 & #2 - Lawsy carriages, E3D v6, Rumba controller board, mirror bed plate, X motor fan, upgraded PSU & Mica bed heater
SD4 #3 - in the works ~ Folgertech FT-5, rev 1
Printit Industries Beta Tester - Horizon H1