and can a person check the one they have.
Yes, rectifiers are checked using a voltmeter which has a diode test range. I think most rect assemblies are two phase or three phase. The former have a total of four diodes, wired as two center tapped pairs of diodes. The 3 phase assy has six diodes wired as three cenetrtapped pairs.
The meter will tell you if they are blown.
i would hate to buy a new batery and screw it up cause it didnt charge it
Install the battery and put a voltmeter across it. It should read about 12.6V. Start the bike and rev it up to above 2k RPM, and the battery voltage should come up to about 13.5 to 14V quickly. If the battery stays down at the initial voltage or drops a bit whwn you start up, it means the charging system is not charging the battery.