Inspect the trigger contacts located on the backside of the trigger for any corrosion or damage.

Inspect the trigger contacts located on the board for any corrosion or damage.

If replacing the trigger/switch board due to faulty trigger, you should inspect trigger contacts listed above to be sure there are no discontinuities or debris prohibiting full contact between the trigger and board contacts. It may be possible to fix this issue without replacing the board. If so, stop here reassemble in reverse order.