JIM HOLSONBACK wrote in a message to JASEN BETTS:

 JH>                  +12V  Pos Out                    Neg Out
 JH>                            |                          |
 JH>                            |                          |
 JH>                     'MYSTERY BULB '                   |
 JH>                            |        4000 mfd          |
 JH>                            |       +     -            |
 JH>                            |---------| |--------------|
 JH>                            |                          |
 JH>                            |                          |
 JH>               |-----MP-----|----MP-----|              |
 JH>               |                        |              |
 JH>               |                        |              |
 JH>               |                        |              |
 JH>             15VAC                     15VAC         CenterTap 


 JH> The "MP" are those mystery parts, now both burned up, and 
 JH> completely into two pieces.  I don't think they could have been 12V
 JH> 3A bead-shaped diodes, because they are only about the same size a
 JH> maybe 1/4 Watt resistors, and I think this unit was built before
 JH> the time of bead-shaped diodes..

This confirms my opinion on it,  that those in fact _were_ rectifiers --
put 'em in there with the cathodes connected to the + lead of the cap,  and
it all makes sense.

 JH> I don't understand this circuit at all, but afaict, that "mystery
 JH> bulb" is the only thing in there which could possibly be a
 JH> "rectifier". 

I don't think so.

 JH> I don't see anything which could be called a 'circuit breaker', 
 JH> unless it is those two (now blown) mystery parts.

Nope.

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