The main maintenance part are the liners inside the mixing chamber. These are recommended to be exchanged on a regular basis.
The diffusion panel: for B&W a visual inspection should be good enough
The filters: The color head I have is rather old but still running on original filters. The filters should not degrade, but to be sure, you´d have to measure. Eyeball won´t do. Unless you have particular reason to be suspicious, I´d give it a try and test if minimum and maximum contrast are satisfactory. With a few test strips, it is easy to find out. If contrast is good, the filters are fine for B&W printing.