OK, so you have changed the voltage regulator/brush assembly and the charge light is still "dimly" on? As Johnny says, if it's not broken don't fix it, but if you are experiencing electrical failure (bike dies because of dead battery) then...
You need to get a voltmeter and check the voltage across the battery while the engine is running at about 2000 rpm, it should be about 14.2 to 14.8 volts (average). If not, then start by checking/cleaning your electrical connections starting at the battery, then starter motor ground and positive/negative power connections. Electrical connections must be clean and tight on helicopters, boats, and all other vehicles which use batteries and generators/alternators. Battery charging issues on older machines are commonly a result of corroded connections, a bad battery, or defective generator/alternator, likely (but not always) in that order, but that's just my own experience... There are of course other issues depending on your individual situation, hope this helps to point you toward a solution...
Eric...