Well on the pickups, usually "Noiseless" pickups have covers on them that say "Noiseless". I could be wrong here but I don't think regular single coil covers actually fit...something about larger pole pieces or slightly different spacing or something. I seem to remember having tried my regular single coil covers on my VN's at one time and that they didn't fit. That said, if they don't say Noiseless on the covers and you bought the guitar used, I might suspect that the person who sold you the guitar was possibly yanking your chain a bit there and since you say the 250k pots do sound better, I'd suspect that might be the case but without seeing the pickups themselves or hearing them at least, it's really impossible to say.

Either way, for all intensive purposes most noiseless pickups are basically a stacked humbucker...that's what makes them "noiseless". On it's own, any traditional single coil pickup produces a 60 cycle "hum"...aka noise...unless it's paired with another pickup. This is why Strats equipped with standard single coils sound so different in the 2 and 4 positions...that middle pickup is reverse wound so when it's combined with one of the other pickups, it cancels the noise. A stacked humbucker basically does the same thing by including that second coil right in the same package.

BTW...just for the record, just because any given shop is "Fender Authorized" (or authorized by any other company) doesn't mean the tech actually working on your instrument it. Good analogy here...when I used to be a computer hardware tech, I once worked for a shop that was...well...they were certified by just about everyone. IBM, Lexmark, Compaq, Epson, Toshiba...you name it. As a hardware tech in the service department I did work on just about all of those brands but I was by no means "certified" with most of them...back then the only certs I really had was my A+ certification and my basic HP certs. Now in my own case I was well trained and I knew my stuff so it wasn't really a problem but the point it that just because a shop is certified at something, doesn't mean all of their personnel actually are. More over I would also add that even if a tech is certified, that doesn't always mean that he/she actually knows what they are doing. Again in my own case as a computer tech, I actually passed the Mac portion of the A+ certification and to this day I still don't know crap about Macs (other than that I don't like them). Same thing with auto mechanics too...I've known a few ASI certified techs who probably couldn't change a flat tire if their lives depended on it! LOL! When it comes to a tech and their actual capabilities, as they say; never assume.

Now on the high E and B strings going flat, the first things I would check would be the strings themselves. Do they have a lot of windings on the tuning peg where they can get unseated easily"? Is the string perhaps hanging up on the string T (the string T is there right?)? Have you tried putting a tich of graphite in the slots at the nut? Any problems at the bridge? How's the intonation on those strings? Quite a few things to look for there. With something like this when push comes to shove I usually try to use a "detective" approach...start at the tuner...does it turn smoothly or is there some "slop"? If the tuner is ok, then look at how the string is wrapped (again this is where a lot of people screw up). If that looks good, check the string T then the nut and just work you way down to the bridge eliminating things as you go. In the words of the immortal Sherlock Holmes, "Once you've eliminated the impossible, whatever you have left, no matter how improbable, must be the truth",

Peace,
Jim

Thanks Jim. Apparently, I do not possess Sherlock Holmes's powers of observation. Since reading your post I looked at the pickups and word "Noiseless" is on the face of the pickup as you said--although in my defense you have to look at it closely to notice it. I think my "certified" tech should have noticed this. This makes me think that the 1 meg pot in the guitar was bad. Although the 250k pot probably sounds better than a bad 1 meg pot, I think I should try a good 1 meg pot to see how it sounds.