Sun tachometer schematic internal board?

[sdowney717]

This would be for a marine Sun Tach from 1977 for a v8 engine
I have 4 of these and one of them when powered with 12 volts, the meter needle goes all the way to max 6000 rpm with or without out the distributor sending wire hooked up.

I have it all apart and was wondering if any electronic guru has any knowledge of the simple circuit board which has a few resistors, capacitors and two transistors.

[sdowney717]

I checked the resistors they are all in spec except R2 which reads slightly too high for the tolerance level.
Both diodes I unsoldered one leg and they seem to work block one way flow the other.
Two capacitors, also seem to work, charge and discharge on the digital multimeter. The blue and yellow ones.

So I am left with the transistors as likely being a problem.