I know this is an old post, but I'll throw in my 2 cents...
For those bearing on that tension arm, since they are easily accessible to the side of the bearning, pop in small holes on that side of the bearing cover when you start to noctice them going dry and re-pack the bearing with a grease needle. Be sure to rotate the bearing and try to get that thing right full again, then clean up the excess grease with some brake cleaner or de-greaser/gas and throw on some silicone over the hole. You can do this to all three of the rollers on that arm without even taking the rollers out. Be careful with the drill, you don't wanna break off your bit inside the bearing. There are some rollers on the top you can do that too as well.
I do all the idlers every fall after I wash the baler, and do the main drives and the idler behind the auto tie pump every 2 years. A little redundant, but I know it's extended my bearing life compared to when I used to just change em when they went. Saves having to mess up a sunny afternoon cause of a smoke show in the rearview mirror. Bearing ain't gettin any cheaper either as I'm sure we are all aware.
