I would like to install a Sensi thermostat which requires a c-wire. I am planning to run a new thermostat wire, since the old one was 18/2. I am trying to figure out the correct way to wire the c-wire for the new thermostat wire, if possible. The wiring diagram for the boiler can be found here:
The set up for my boiler is on page 30:
Also, see the similar question How to connect c-wire to Burnham Series 2 boiler?. It seems in this case that 24v power was able taken from an extension plug for unused accessories, which is not applicable to this situation as far as I can tell.
Thanks for any help that you can provide!
Edit: Here are some additional pictures: