IBM 83-key questions (repair and color)

Re: "The spacebar - beyond the switch - has a small "C" supporter that keeps the bar horizontal and makes any pressure in any point of the bar activate the switch" This is called an "equalizer" mechanism, and all keyboards have it on all large keys (it's usually present on the enter and shift keys as well as the space bar, and often on a few other keys). These can be a real bitch to get reconfigured properly, but it's a purely mechanical task, and with some patience, if this is the problem, it should be fixable. It's possible, however, that this isn't the problem. Do NOT take the back of the keyboard apart as a first step, rather, remove the space bar (being very careful not to break the equalizer mechanism and noting in detail how it is attached). There is a metal plate inside the "switch" that serves as the actual contact point, this can become dislodged. Or there might be dirt in the mechanism. It's very rare that these can't be fixed, and fixed without any new parts, unless something is really broken. More common it's just dirt or some mechanical part that has become misaligned.