When i put my K1 1K on the rear stand , and spin the rear wheel slowly, there is a particular spot where the rear wheel whistles, (oh maybe i am hearing friction noise, but in any case, it only occurs at one particular spot).

I have also noticed that my chain has been getting really slack lately, usually within 250 miles after adjustment, (adjusters are firmly in place and never loose.)

Replacing the chain/sprockets is not a problem for me, but just wondering if there is something else going on. Any troubleshooting tips will be greatly appreciated. :scratch

Chain sounds like it is near death.
Feel check the bearings for roughness. R&R the chain set first and then recheck for odd noise, etc.

Problem solved. Turns out chain and sprockets were shot. Got them replaced with vortex sprockets and ERV3.
Gearing not changed so i am still maintaining -2,+6