Hi Stu,
No, I looked through the service manual and op's manual but didn't see anything that would help so I put it on the backburner until I get my clutter of rigs tested and put up to give me some room. If I don't figure it out I may send it to Kenwood, unless someone who owns one can show me the way.
I too heard alot of good about them which is why I bought it, but if you're looking for the best 2m all mode mobile (IMHO) it's the Kenwood TM-255. I had one of those and have regretted selling it ever since. It's also newer than the 751.
Regards,
Woody
PS - Okay, you got me thinking about this so I blew off the other rigs, and found that if I ground VR14 (tight squelch), I get the radio Hiss back. Because it comes on for a second or two when first powered up, it could be a capacitor, but with blurry schematics, hard to trace, so I made just ground it and not worry about it (after all, I bought it for SSB so I won't require squelching). I guess I got a lemon, but don't let that deter you from buying one.