I like to fix cars, hack electronics, fix TVs, projectors, computers, board level repair ... all that.
There are some simple rules for my success. One is to use the proper parts ... as close to original as possible. Just try to return the machine to it's original operating condition. If the machine doesn't get fixed (or lower performance, fails quickly again, etc.) you are just wasting your time.
With a projector, since the actual light is such an important part (intensity, color temp, etc.) ... I think the Epson engineers know more about what is best. They make these and have for a long time. Once you embrace that fact (with whatever it is you are fixing) you start being successful and gain some confidence.
Another rule I use all the time everyone knows is "Don't fix things that aren't broken". A related rule is "Don't make easy repairs hard".