Z belt adjustment?

had some issues initializing tonight! the stepper for the z axis will not stop upward travel. the belt for the z axis seems really loose to me? i have tried adjusting the screw on the top of the z. that did not work. if i apply slight pressure to the belt it seems to initialize fine. is there any belt adjust ment for the z axis?

my belt seems loose also. mid print sounds like the z axis motor was clicking during the print and last 20-30 layers were not smooth. 

I often find clicking is the extruder motor struggling to feed, normally because of a burr on the insider of the reel. 

I made myself some clip on 608 bearing holders for the spool holder but I need to do a MK 2 version because they're shit tbh.

i ended up removing the top pulley bracket. there is a metal post that goes into the aluminum extrusion. added a washer to that post to increase belt tension slightly... seems to be working fine now. the other 2 axis are spring loaded with tension. wonder why they didnt do the z as well?