I assumed some stuff. Maybe wrong.
If your front sprocket was worn out (hooked/pulled)...and your chain was worn out (at the end of mechanical adjustment, measured overlength based on the pin-to-pin measurement)..if the rear sprocket was on for the duration, it would be worn, too.
With a new chain (108) and 12/47 combo, you should be around 4-5 or so with correct slack ( 2.25- 2.75 measured at the end of the slipper). If you're 6 or over, things got tweaked a bit.
The oem guide DOES rub on an o-ring master link clip some. The FRP unit is supposed to resolve that. Have heard from at least one that it didn't.
I just replace my clip once a year or so.
Like O&S says, if it's done, it's done. Next time, if you HAVE all the stuff, certainly better to do it all the same time.
Good luck with the health of your chain!!
Now...don't you feel better? Might as well! It's free!!
Time to go out for a ride!!!!!
btw...did the noise change at all with the r/r of the sprocket?