If it has a C1 next to it you can bet it is a
capacitor.
You should have rows of them on the card.
Nope, I'm sure that it was a diode. The ends of it
were still on the leads. There is another one next
to where it was labeled "C25".
Is it is the one by the resistor and transistor?
Or the one by the two 'normal' looking capacitors on the other side?
There are no transistors on the board. The diode is in
the corner, near the power connector.
Just for reference, the main component on the board is a
40 pin IC labeled:
AMI KOREA
SHUGART
16271-0
8130B1M
There are only three caps that I see on the board. They
are the little silver can types, no ceramics. They are
labeled "C17", "C22" and "C26".