Morton your focuser looks like the GSO types of which I have 5.....so having admitted that here is what I think.
The ball bearings on the fine focus are supposed to look like that. I have found the grindy thing happens every now and then with my GSO focuser's too. The grinding sound problem was solved by unscrewing the grub screw and moving the knobs out of the housing and the fine knob away from the corse knob giving them all a tiny bit of wiggle room.
Works for me, only discovered after pulling apart cleaning etc. I guess the tolerances GSO focusers are built to is good but not great. By contrast a Feather Touch on my Newt stored in the same place as my two refractors never has this problem.
Might work for yours
Matt