Cobra 139XLR receive tune up or mods?

Hi all, I am sure this has been asked before but I have a Cobra 139XLR (D858 chip), receive seems "decent" but it is somewhat noisy and I know I can improve the receive. Can anyone tell me what to align for receive or perhaps some simple mods. I have a signal generator, VTVM, and solder/desolder equipment so any information would be great.

Thanks to all, Adam