You probably don't need to replace all your electrolytics. Start with the big blue Spragues (you can up the capacitance if you want to tighten up the bottom end of the amp) and any that show obvious signs of leakage, like bubbling, corrosion, or oozing goop). You should also take a good look at the solder on the PC boards--solder joint do degrade over time and that may be part of your problem. Most importantly, don't do any of this unless you've got a quality soldering iron--the cheap ones will only frustrate you and potentially create more problems than they solve. Lead free solder is a pain to work with because of its higher melt point--I strongly recommend the leaded variety. Mouser is probably your best bet for capacitors for this kind of project--there's better sources for high voltage caps as used in tube amps, but for solid state stuff Mouser is pretty much my default source. Plus they will ship USPS Priority, which is generally cheaper and quicker than UPS or FedEx.
