Marshall Origin 20 schmatic?

hi there anyone got a schmatic for the "marshall origin 20" model or120c.

I have not plugged it in yet but am told it goes ok for a couple of minutes the just fades out.

schmatic would be good or if anyone has experience with this model and has ideas as to cause of fault please chime in.

all rdy noticed that the output trany is connected to circuit board with spade connectors which are quite lose, but i don't think that's the problem