Two on the top each side - 3 in the back in front of the media roller - so remove the roller
The two you removed from the rear top hold a piece of metal to keep the piece you are trying to remove.
Also under the front blue cover might be some - cannot remember, and going to eat.
The noise is definitely coming from the white gear for the head drive on the left side of the unit. I see 2 long screws on the left side, and 4 on top of the gear / belt assembly. I'm not sure which ones to turn which way, but it is this white round gear with teeth where the clicks are coming from.
I suspect it gets worse with friction / heat, as the more I print, the more it clicks and the louder it gets.
The metal tabs that I accidentally removed have been put back into position and are marked with blue dummy tape :-)
Here's a better video of it:
Second image, yes. Set on either side of the printer.
You've Got Mail! in my AOL voice
I got her put all back together, except for 2 black screws near the load lever on the chassis cover. I just couldn't get those 2 holes to line up.
The belt tension before was extremely tight. During printing now, the belt bounces up and down a bit. I am getting some mild clicking, but I think it is from the belt bouncing up and down. I'll give it a while and see if it settles down.
I'll save the 2 screws for another day when I have to take covers off again.
Just a general observation, it prints much quieter now. I believe the overly tight belt was creating other noises, not just the clicking sound.
I'm leaving the tape over the tab screws :-)