Sorry guys, but the old WD-40/lubricant is not working. I used a pen light to look into the valve tubes and there was a build up of corrossion/gunk on the bottom valve caps. The WD-40 did break up the corrossion inside the tube but failed to loosen the caps. I used enough WD so that I had to wipe off the excess from the horn. I also let it set for 30 minutes....three times. I can't get a good hand grip, even with help from the rubber jar openers, the threads are too fine and the caps to too small. What I need is some leverage to twist off the caps, and that calls for some gripping tools. The only thing I have in the house is automotive and plumbing grips which may be overkill when it comes to a musical instrument. I guess I'll take it to the shop this evening and let the pros handle it.
Still plays great without the maintenance, no dents, valves work fine, it only needed polishing. I don't know how long the trumpet may have been in "storage". I purchased the horn through E-Bay, and the description said it belonged to an old pro in the Pheonix area that passed away. The seller sold the horn for the widow, so I only assume a pro took care of the instrument.