Hello Joe,
Taking the machine apart is a good idea. Also gives you the opportunity to give the machine a good scrub, and it will probably need that.
Disassembly is pretty easy, but, if you have a digicam, it helps to take pix (plus it's fun for others
1) You start by removing the bolts on the either side of the group, and take off the upper part of the front. Remove the wire clamps from the switch. Take note which wire goes where, or just label them.
2) Next, the machine on its "back", and remove its feet - the metal exteriors of the rubber feet are bolted to the frame. You may have to use pliers if the bolts are really tightened.
3) When that's done, you can remove the lower part of the front (which holds the drip tray", and just slide the entire machine out of its plastic shell. With the machine's halfway out of the shell, remove the wire clamps from the power cord. Again, use labels, or something.
4) Now you can remove the top of the boiler, with the lever group, from the container. Easy, just four screws in the corners.
5) Lastly, if the frame (two steel "L"-shapes with a cross bar) is a bit rusty (not stainless steel, alas), you might want to remove this from the container, and give it a paint jobbie (Hammerite, or some such). Again, four screws.
Cleaning...
The Mini Gaggia is an espresso-only machine, so the boiler doesn't have to be pressurized. IOW, the group is fed by gravity alone. One downside of that is that on the downstroke of the lever (= upstroke of the piston), some crud gets sucked into the boiler. Not much, but if the machine has been used for years without cleaning, the boiler isn't a pretty sight (see pic below).
The Mini Gaggia's setup isn't unique, and other machines with gravity fed groups usually suffer the same problem.
Use an espresso cleaner that isn't corrosive to aluminium, and let it soak for a few hours. A scouring pad afterwards does a nice job.
Regarding spare parts - I hope you don't have to change the piston gasket, because it's damn hard to find. If it looks any bit decent (not dented or torn, or anything), and the rubber is still pliable, just leave it on the piston and just give it a bit of a clean. It'll probably seal better after a uses. If necessary, wrap a little teflon tape around it - work wonders.
The shower screen - I know the Mini Gaggia screen is also used by one or more other mfr's, but the name(s) escapes me at the mo. If the screen of its identical twin, the MiniMoka M-400, is the same as on current date MiniMoka models, I could just drop by the Dutch importer (they have a shop basically around the corner), pick one up & put it in the mail for you. Best is to contact MiniMoka first though. Their email addie is:
info@demoka.com I found their customer service first rate.
While your at it, ask if they know a source for the pf gasket and the piston seal.
If anyone's interested, I've put some more pix up at:
http://webdisk.planet.nl/rjeroenv/default.aspx - check out the Mini Gaggia folder.
Cheers,
HV