Fender Hot Rod Deluxe. Works great except when I turn the amp off it crackles pretty loud. It takes about 5-10 seconds for the crackle is heard. If I turn the standby switch first, then wait a minute or so, and then turn the power switch off, no crackle. Any Ideas

You probably need a new input jack on the amplifier. When they get loose the connecting wires can crackle, but plugging a guitar in stabilizes them (no more crackle).

The Fender Hot Rod Deluxe shows a 2-button footswitch as standard but I'm confused. This link shows it as connected to the amp via a mono cable ... FENDER Hot Rod Deluxe DeVille Footswitch which is impossible using two switches. Normally it's a stereo (tip, ring, sleeve) with tip to sleeve being one connection, and ring to sleeve the other. Good luck with this one.

If it worked before you changed the tubes, it is possible one of the replacements (probably a small tube) was bad... it happens... Another possibility is that a socket pin has gone bad or a pin has broken or bent off... again probably one of the small ones... 12AX7/12AT7 or equivalent.
Swap old ones back in one at a time.

This could be any of several problems including a failure in the power supply filtering, a tube that has shorted, or a broken ground someplace. Take unit in for repair.

Using a common lead pencil, gently tap on the smaller tubes in the unit, listening for noises and crackling to change and the drive channel changes.

It is normal to get a slight twang when doing this from the microphonics of the tubes, however, the crackling and up and down volume points to a bad tube.

In YOUR amp, take a pencil and tap teh sides of the tubes GENTLY, listening for any crackling... note SOME microphonics is normal in the preamp stages.

Since retubing it fixed it once, it is likely either a tube was bad OR a pin of a tube wasn't quite making so replacing the tubes cleaned it and made it work. Tubes DO go bad, especially when they are vibrated like in these amps... BUT don't just replace the lot, try to find which is at fault..

On your friends unit, LIKELY an electrolytic bypass capacitor for one of the reverb preamp stages has dried out and needs replacing.

Here is a link that might help:http://www.geofex.com/ampdbug/ampdebug.htm Unless you have the tools and experience to work on your gear it is always best to take it to someone who is qualified to work on that particular amp. Your local Fender dealer should be able to recommend someone.

Your amp has two channels - "normal" and "drive." When you are on the normal channel, the "volume" knob controls your gain. In the "drive" channel, the drive knob controls your gain. In both channels, the "master" knob limits how loud the amp will get.

Most likely, you are on the drive channel, so the volume knob will have no effect. Try pushing the "channel select" switch. You should notice the channel indicator lamp (next to the drive knob) turn off. When it is off, you are in the normal mode. Yellow = drive, and red = "more drive."

Experiment with different settings to get a variety of tones.

To get the most out of this amp, try reading the manual, available online here:
http://www.fender.com/support/manuals/pdfs/manuals_elec/guitarpdf/Hot_Rod_Deluxe.pdf

Have fun - it's a great amp.

First try turning the volume control down before turning switch to operate.

IF this seems to fix it, IF the unit has a tank reverb, the vibration of the reverb springs MAY be causing the problem. The solution then is to reduce the volume before applying power WHICH is a good idea anyway... from an electrical engineer.

Ah yes, the Fender Hot Rod Deluxe. I have seen more of these in my shop than any other amplifier!! I have even sent recomendations for design changes to Fender about this amplifier.
Sadly, your amp tech may be correct: while the amp is within working specs, you can still have an issue with a bad socket. The cheapest thing to try is to replace the preamp tube(s) you think may be causing the problem. If the problem persists, it may need to be serviced on this issue (by a different 'certified Fender tech'). In defense of the last tech you had work on this amp, these amplifiers have a brittle design and do not gig or travel well (there are a minority of these amps made that do perform). Fender tried to do too much for the price on this model: best advice is to fix it, sell it and get your tone with a more stable model made by Fender (like the new vintage re-issues). Fender, like Marshall, has for years been having problems when they get too far from thier 'working reciepe' of what made them great companies.
You likely have a socket that needs re-tensioned, or a preamp tube not behaving. If it is not these, then a tech had to dive in the house of cards that is this circuit. Sorry for the bad news on this, but it is the truth. I only take on Hot Rods that 'appear' to be fixable. I am a development engineer, build amps from scratch and fix them for the local music shops, and my success rate is a dismal 60%-ish percent on these...
Thanks,-mike