power issues, alternaator?

[ecko]

So in my 2sc equiped corona,
when driving at night my lights on dash and healights get brighter and dimmer just driving along not related to revs at all tho,

now first thing ive checked is earths and all seem ok,
next i guess may be alternator regulator?
i almost replaced it but its not a simple plug type and requires soldering,

am i going on the right path?

[oldcorollas]

or the brushes in the alternator are juuust geting to the point of beign too short.
check them before reg.

but check actual voltage first