Meths and cotton buds will be fine if you cant get your hands on the proper Alcohol stuff, used to use Meths all the Time on 2" Studio Machines and again when I was at Laskey's and Comet's moons ago.
On Cassette decks, push play without a Cassette in, dip the Cotton Bud into the cleaner pull some cotton off slightly from the bud (making it bushy) then catch it on the rolling pinch roller(s), the cotton will wrap itself around the pinch roller pully whilst its running and give the rubber roller a good clean for about 30 seconds then pull off.
Heads, look for tape wear across it, where the tape will run across it, if its not worn, just clean it, if its worn there fairly easy to replace.
Azimuth alignment shouldn't have moved, as the adjustment screw should have been locked down with varnish or lock tight, if it does need adjusting, idealy done with Dolby Test Tape and Oscilloscope, or a White Noise Tape and adjust by ear.
Belts and Clutch, replace or if there ok whip the belts off and clean with meths an then a good scrub with fairy liquid in your hands, dry, check for cracks, long time unused bends and replace, clutch, check operation and its not dried up, re grease or replace if needed.