Lloyd, alignment is a tricky business. We know there are two parameters, overhang and offset.
Overhang is relatively simple to set. It should position the stylus tip in position to trace the proper arc for a given arm (distance from pivot point to stylus tip).
Offset can be more difficult to set correctly. It is critical for any stylus, other than a conical design, whether it is a simple elliptical or one of the more modern narrow profiles. This sets the profile of the stylus at a right angle to the groove so it reads right and left sides of the groove directly opposite one another. Said another way, it "traces" the groove more closely to the way the cutter stylus created the master groove, thus lowers tracing distortion. This relationship may not be perfect across the record with a pivoted arm but will be very close when set up carefully.
Depending on whether the cantilever is bent, the suspension failed, or it was not manufactured correctly, small errors may be corrected by aligning the stylus end of the cantilever with the appropriate line on most protractors (note here the cantilever is used for alignment, not the cartridge body). This is the best way to set the stylus tip relative to the groove, unless you have an oscilloscope and appropriate test record.
But there is one more consideration. If the cantilever does not appear to be straight out of the cartridge body, the other end could be offset inside the cartridge. If this is the case, the proper alignment between coil and magnet may not be correct, then balance and crosstalk may suffer. This may only be corrected by rebuilding the suspension for the cantilever. Also, if the cantilever is bent, an angled alignment may correct at the stylus tip but that may in turn push the magnet/iron or coil toward one side inside the cartridge body. Here is where I disagree with Elizabeth, you may align the stylus tip correctly relatively to the groove but depending on the problem with the cartridge, the coil/magnet alignment may not be correct.
I just worked through all this because I bought a used cartridge with an angled cantilever. And in answer to your last question, I believe a Grado rebuild is actually a replacement.
Good luck.