Worn Valve guides

[Nima]

Hi everybody:
I just read a thread about using vacuum gauge to ajust a carb. One of the thing which was mentioned was " if the needle vibrates heavily at idle but become steadier as rpm goes up, is indication of Valve guide problems".
Well, being a newbie here, other day I was playing with my carb and new vacuum gauge trying to set the carb at it's best, then I noticed that when the vacuum gauge is connected to full vacuum, at idle it vibrates between 15 and 20, very fast. Is there any other sign(s) for valve guide failure or the above test is written on stone? If it is vavle guid problem, how can I fix it? Thanks.