I've seen a number of requests for the location of all the grease points on these machines, and there is no definitive list in the manual. This covers the UT400, but other Coleman/Hisun models should be similar.
Tools:
First to grease your machine you need a grease gun and some NLGI#2 grease. You will find it helpful to buy a needle attachment as pictured here, due to poor clearance on some of the U-joints. The rest of the zerks use the standard attachment.
Technique:
Wipe any dirt/grease off the zerk before greasing to prevent pushing gunk inside and causing excess wear.
Push the grease gun on the zerk at a straight angle and give it a few pumps. You will hear an oozing noise or sea grease coming out from the outside of the greased area when you've put enough grease in, a few pumps should be plenty.
If it's just oozing around the zerk you either don't have a good seat with the gun, or the zerk may be rusted and the check ball frozen. Try seating it again and regrease.
Wipe up any excess grease when youre done to prevent making a mess.
Greasepoints:
Rear A-Arms are greasable with the wheels on from the rear, I took the picture with the wheel off for easier visibility
That's it. All other Hisuns should be substantially similar.