fine tuning gears
 

Hi there, I recently bought a road bike with a Shimano 105 group.
Although in a month or two, it will get it's first free check at my LBS; I do like to fine tune the gears. When on the biggest/or middle chain ring, I have some problems with the proper placing of the chain on the 4th small ring. It shifts OK, however sometimes "misses some teeth" before settling. This happened a few times, and although it is a bit annoying it usually settles after a bit of fiddling. I loosen up/or tighten the gear cable by turning the nut on the downtube. However, what more can you advise.
As said I will go to the LBS, but first I like to try something myself...

check your rear dérailleur' s hanger ,it might be bent. have the shop check this with the tuneup.