Here is a simple onsite test for checking bearing condition with grease ferrous debris analysis.
When the equipment is available, get a small grease sample from the bearing and dissolve it with a solvent (I use Misty Industrial Cleaning Solvent) in a small, clear oil sampling bottle. If you have multiple bearings, try to use the same amount of grease and solvent for each.
After the grease is dissolved into a liquid, tape a small round button magnet to the outside of the bottle.
Tilt the bottle at an angle so that the liquid flows up towards the cap on top of the magnet.
After 30 minutes, stand the bottle straight up so that the liquid flows back down and let the ferrous dry inside the bottle with the magnet still attached. After drying, remove the magnet and you can determine if there is any ferrous metal.
You can use this method with multiple samples in order to determine if one bearing is wearing faster than others.
I have used this method for years and, as a result, have identified several abnormal conditions.