Nice looking Surfer! "C" is the spin target relay, but you'll probably find your problem is with the "KS" advance unit relay, which is mounted under the playfield on the left side. It has its own jones plug so you can remove it for servicing, which may be just a matter of degreasing the wipers, etc. I think there are discussions on here about dismantling and adjusting these units.

When C is manually activated, it should add 10 points (with chime) and advance the KS stepper. The spinner switch is the only one that activates C, so make sure it's clean and adjusted.
The KS is technically an AS type stepper, there's detailed info here, http://www.pinrepair.com/em/index2.htm#steps, scroll down to the end of the chapter.
The knocker coil needs two wires, there should be a black one in that bundle for it. The 5195 coil is what the chimes use, 5194 is what is spec'd for the knocker, but I guess the 95 will do in the meantime. The sleeve on the knocker coil looks displaced, should be down inside the coil.

If continuity is good between C and KS, then the KS coil is suspect.
The knocker's black wire is on the middle chime tab. The blue wire links all the chime coils to their black wire on the left.