If you are up for this you can try this......it is messy so lay some scrap hand towels down to limit the mess.
You will need a spray can of brake cleaner with the red little straw that shoots it out.....
Before attempting cleaning, switch off the sub power/power and wait until the heater and dryer cool (approximately 30 minutes).
First use this cleaner to completely clean the track top and bottom that the carriage moves on...the full length..spray very lightly and it won't go all over the place!
Then spray into the tracking where the carriage is sitting from both sides....make sure you protect the rest of the machine from any over spray that will be generated...
This should loosen the carriage up enough to start moving it slightly from side to side....continue the process until it starts moving normally....once you achieve this...let the machine sit for a couple of hours until all the brake fluid has evaporated.
Lastly you will have to re lubricate using lithium grease. To do this place a small amount of this grease onto one of your foam cleaning swap sticks. place some on both the bottom and top rails. Slide the carriage over the area several times to get this grease to the bearings within the carriage...repeat a second time. Wipe off all the excess grease and that should do it. This entire process should be performed as part of your maintenance schedule.
here is a link to an article about this topic....It is not the same machine but you should get an idea as to the steps.
https://techsupport.signwarehouse.com/mutoh-cleaning-bearing/