help me with this.............

I have a kenwood kt 7500 tuner
cj pv 12 pre amp
cj 2500a amp
Marantz  cd5005 cd player
when I listen to the tuner for any amount of time then go to the cd player, I get static and usually one  of the channel don't play for a minute or two.  then everything is fine.  what is that, is there a problem in the system chain or the cabling.  let me know if you have or have had this problem.thanks.......................... 
There could be an issue with the pv 12 selector switch that you use to go from tuner to CD, then back to tuner.  It could just need its contacts cleaned or if it has been used a lot over years, the selector contact could have developed a flat spot from wear.  If that's the case you would be looking at having the selector switch replaced. To diagnose the issue, try working the selector switch and see if you hear the static as you toggle from one source to another. Again...this is a possibility not in any way a certainty.

you may be right. another thing I have notice is when i play my tv thru the stereo, i can still hear the tv sound though faint .....when I change to another source.

Hearing another source that’s still on isn’t that uncommon.

On the other issue i agree that it’s most likely a dirty input selector, my suggestion would be until you can have all the controls cleaned and lubed exercise them a bit. By this I mean, turn the amp off so no transient thumps, then work all of the controls several dozen times each. For example, rotate the balance knob clockwise then counterclockwise back and forth rapidly over and over. This will wipe away most any tarnish that may have built up on the contacts and usually alleviates most issues,for a time. This in no way replaces a good cleaning, but should help temporarily.

yeah, that is what I do, will proablly get unit cleaned and lubed like you said.......
have a cj pv 12 and pv10.  thinking of getting a new classic or parasound p7...real afraid of the used stuff.   I do like
and modwright preamps, two have gone out of business and that amp is pretty old.