2008 Tacoma Heater Only Blows Cool Air, Air Mix Servo Working OK

The air mix servo is working OK, and I can rotate the damper drive shaft by hand,(with the servo removed).
From reading other posts I understand there may be pin in the mechanism that can break and may cause my issue.
Where is that pin and how to repair?

 

No heat issue resolved, all servos and dampers working OK.
Found another thread that suggested checking coolant level, hey that should be OK the shop that's been doing my ol changes gives me a list of what heve done.
I've used them for years and for the $39 they charge it's not worth crawling under the truck.
NOT anymore, coolant level low, reservoir empty, radiator level well below filler.
Added Peak Asian to full mark on reservoir, topped off radiator tank, now heat is working fine.
Since my faith in the shop was broken I checked the oil level and power steering levels both needed additional fluids.
Needless to say, I'm forced to return to doing my own service work, might be inconvenient, but at least I'll have a better look at hoe the 200k miles Taco is doing.