Need a line stage preamp

My Acurus LS11 line stage preamp (early 90’s vintage) seems on its way out.  Or I think so.  I’m noticing that the right channel doesn’t seem as “peppy” as the left channel.  I’ve deduced this through various tests and I’m left with my diagnosis.

that being said, I like this little preamp, and I could send it somewhere to be fixed. On the other hand, I could also buy a new or used preamp, but the “law” has laid down the law and she’s nixing anymore serious spending. 
FYI, I use the preamp to run an ARC Classic 60 amp.

My budget is only $500, so unless I can find an equivalent pre I’ll be forced fix it. The question is who does good electronic testing and repair or can anyone suggest an equivalent component?