Here is a layout of the circuit board (component side; parts in parenthesis are on circuit side of board). Q2 is in the upper right-hand corner. Can you suggest a replacement ? I can find no information on the APOLLO 3420 device, so I have no idea what it is or does. It appears to be a ceramic case, with the name "APOLLO" and the number "3420" printed on grey plastic that is shrink-wrapped around the case. There are no other identifying marks.