Hello, just joined your page, thank you for having me, I just purchased my first K40 Laser, got it Friday and when I unpackaged it, the Side Belt, had come lose on one side and was laying in the bottom, I have no experience or knowledge about this machine, is this a hard belt to repair ?? if needed replace ?? for someone with no knowledge of this and it’s operation ?? I am a small Mom and Pop Woodshop, who wanted to try something new and hopefully expand my small business in a new direction, I pray this wasn’t a mistake, any suggestions or advise is greatly appreciated.
Can you post a couple pics of it so we can see?
From what you described I’m thinking the head mounting screw. The belts are not a loop but a section and the sections are held together with a screw that pulls the head around or bar being the sides…Y axis belt… there are two on that axis.
Should be a fairly easy fix but may take some effort to get to. As Nathan said, pictures would help us to see for sure.
I believe your right, because the end that is loose, looks like it may have been screwed down, has a Horseshoe type end on it, being from the side, that moves the machine forward and backwards, I just need to figure out how to get to it 
@Nathan_Thomas here are 3 different photos of my belt and where it seems broken ?? or come loose
If the remaining belt section is now not long enough because it has torn loose the simplest thing would be to order this from Laserobject
Thank you so very much, very New to all of this, so when I try to repair, I will make you a Video for Dummies 
Y axis belt for K40 repair wish me Luck
Your welcome, lots of help here.
Note:
On your machine there are four holes, two in the front and two in the back of the case. I have not had to do it yet but I believe they are there to access the belts and adjust the tension on them.
I would think you have to move or loosen them in a manner (before belt replacement) that allows you to adjust that tension afterwards.
Maybe someone who has done so will speak up.
Thank you so much I decided tomorrow I would get into it, wish me Luck will let you know how it comes out
Great!
thank you for the advise, I will let you know how I do, every time I am about to get started, something more urgent comes up eventually I will get some me time and get this task started and hopefully successfully completed