preamps

First question I have is on a ONKYO P-306RS. I picked it up reasonably cheap, but the right side channel has less output than the left. Even with the balance to the far right you can hear a measurable difference than the left in output. All the caps look physically OK, that is nothing blown out. I've cleaned all the pots and switches et., but still no difference. I can find a partial manual for the P-3030R which looks real close, but it is missing the adjustment section. I removed the balance POT, an ALPS250K, and the resistance is about 199k on one set of contacts and 228k on the other side. I have been told this won't make much of a difference but I am no technician by any stretch of the imagination. I can solder and unsolder and basically a parts swapper. I know how to use a multi-meter, and have a scope I am trying to learn how to use. If anyone has any experience with these amps or a similar problem maybe I could get some pointers on what to look for and where.

Second question is about an DENON PRA-1100. Would this be a decent preamp? I have a SANSUI XP-99 turntable I am hooking up to a DENON AVR-1909 and it has no phono input. I am also buying a ROTEL RQ-970BX after the first of the year, and I understand that could also be fed into a preamp, or stand alone into the DENON AVR amp. I am just getting back into my records after many years of being without them...since 1984 or so.

Any help would sure be appreciated
Thanks,
Tim