The best method is 'learning by doing', indeed, it won't do any harm keeping your brain engaged at the same time. A little sense of responsibility and finesse won't do any damage either. What I'm actually talking about, is of course, the assembling and dismantling of parts in which liquid lubricants are generally found, they can be either pressureless or also in an agitated form.
This is all about gaskets, in this case we're dealing with so-called 'static-seals', these are gaskets used when when the respective surfaces to be sealed are not moveable. The possiblity of damages that can occur when they are dismantled seems to be high. Thereby, the crudest offences against the sentive sealing surfaces can be forseen, particularly if one uses the respective tools.
The first one that should be put aside is the sharp-edged or angular screwdriver. Using one of these, you could probably get the lid or cover off, however, getting it well sealed back on again is a different story. If people would think about putting it all together again during the dismantling, the respective parts would be spared a great deal of grief. Yes indeed, using a leverage is mostly wise, not however when the surface to be sealed is used as a fulcrum.
'I don't have the time' is a poor excuse, think about how much time you'll need to iron out any mistakes made. Some even use the hammer and the screwdriver as a chisel if they think it will be quicker. No, rather look for a piece which is jutting out (see picture 3), there you might be able to use a plastic mallet. Try to work evenlyand to avoid warping the part which has to be removed. In this case, brute force is simply not an option.
The responsibility is not over when the lid or cover has finally been lifted. Don't attack the remains of the gasket with screwdrivers, knives or sand-paper. Although you may get rid of the gasket, the sealing surface will also be ruined. Soak the remains with a suitable chemical substance before attempting their removal, if need be, even for a few days. A triangular scraper is well suited for the careful removal.
Nowadays, the parts are often made of aluminium, this greatly increases the possibility of damage occurring. Thereby, the manufacturers have put a lot of effort into giving the surface a certain roughness, into which the (hopfully new) gasket can be pressed when tightening the screws (hopefully using a torque wrench). In this case the roughness is desired, not however, with the sealing of parts which rotate against each other.
If such a mishap has occurred, the planing of the part is means a lot of effort and expense. Apart from that, one must take particular care, that the (axial) tolerance of any shaft has been altered when the part is installed again. It may be more simple to fill out the damaged area with a hardening substance, whereby the maximum temperature tolerances must be adhered to.
In any event, the planing of the part afterwards is unavoidable. Freehand planing is certainly very difficult, you can count yourself lucky if you know someone who has a heavy, perfectly level plate. Indeed, one problem remains, as little as possible of the sealing surface should sanded off. Getting the original roughness back again is very difficult to realise. Best of all is, one should take care that it doesn't happen at all ... 05/12