Help?!--Volume Problem on DC-5 Lead channel

Hi everyone!
I have not been playing my DC-5 for awhile. I fired that baby up last week.
Now I am reminded of a problem this amp seemed to always have but which now seems more eggregious-- when switching from the rhythm "clean" channel to the "lead" channel the volume drops drastically. Now, the gain and channel output volumes are set the same, but it sounds like 20+ Db quieter on the lead. Otherwise it sounds okay.
This is bugging me. Anyone got an idea? Do other DC-5s do this?
I would suspect a bad tube-- but the diagram shows that the tubes are generally shared with both channels. Hence a weak tube should affect both channels, eh?
Ideas? Experiences?
I have a bit of experience working on electronics, but I dont have a scope or diagnostic equipment....
Any insights would be appreciated.
Thanks!
Ron

The Basics:

-Clean the effects loop jacks: grab your guitar cable and some contact cleaner push in/out and work it. In fact, do it to all jacks.
-Clean the pots with contact cleaner.
-Replace preamp tubes: roll a known good tube one at a time in all preamp sockets. Don't replace all at once because that's not trouble shooting. If you replace all at once and one new tubes is no good, you'll think that it's something else causing the issue when it may be one tube causing the issue all along.
-Replace power tubes.

Sometimes I hear of LDR's that go bad but I'm not sure exactly how these work and if they can affect this issue.

Maybe a cap or more have had it.

I'm not an electronics expert so I can't say any more.

-B

Hey thanks!
I have not cleaned the jacks but I did rotate in some tubes. I'll go over the jacks.
I did find a short in the reverb tank and have another one on the way.
I guess what bugs me is that when I look t charts it mostly shows the channels sharing the same tubes. So why loud on channel and not the other? The tone is fine on both-- it is just that the overall volume is much lower.
So now I'm worried. Must be some circuit problem.
I am no electronics tech. I have heard of some designs that use a single tube in different modes per channel, but it's beyond my comprehension.
I guess my question could be rephrased-- the DC is like other dual channel amps right? At comparable settings, the sound level should be similar when you change channels. Or something's wrong....
Thanks again.