Long-Term Amp Storage Without Use: Bad Idea???


Hi All.  I've got a nice set of Cary EL-34 tube monoblocks which I haven't used for 2 years.  I put them up for sale, but then decided I'd rather hold on to them for a later day.  That later day could be years from now, maybe even a decade.  I don't expect to pull them out and "exercise" them to keep them in shape.  Is this a bad idea?  I've heard capacitors tend to dry out if left unplayed for too long. Thanks in advance to those who have knowledge in this area. 
peter_s
A friend of mine just lent me a pair of Canary CA-309 valve monoblocks with matching monoblock valve preamp. He stored them in original boxes taped shut in his garage in the topics for about 12 years. They are internally rusted to buggery and don't work. A crying shame given what they were worth new. Now I have to work out whether it is worth spending thousands getting them working and cleaned up.
Not that this is a recommendation but my current Proceed HPA2 (Levinson) amp was stored in a damp (really damp) basement for over 3 years (not my doing). There is a trace of rust on the screws that hold the handles on the back. Everything else looks like new. It has been working normally now for over 6 months. Time will tell if there was any other harm done.
If you want to keep it you have to store it.  
Use good quality storage materials!