"Clean"????? All that crud on the base looks like at least one of the coils has melted down. Have you checked the coils for continuity? Connect an ohmmeter between the Field terminal and the base of the regulator- - - -you should get close to zero resistance. Opening either of the spring-closed points will jump the resistance up to at least 2-3 ohms- - - - -they're wired in series. The coil behind the ARM terminal controls maximum amperage- - - -25-30 amps on most 6V systems. The one behind the FLD terminal controls max voltage against a fully charged battery- - - - -usually about 7.5 V. If the generator is OK, removing the wire at the FLD terminal and grounding it should make the voltage at the ARM terminal increase with engine RPM. Filing regulator points is a VERY bad mistake. It will make them stick. I use a strip cut from an index card or something similar to burnish regulator points, or if the points can be disassembled, clean them with a pencil eraser.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!