Connected the servo motor to the trim tab horn. I had to enlarge the hole in the trim horn to alllow for insertion of the clevis pin. The pin measured about 1/8", so I used a #30 drill for the clearance hole. I should have used a 1/8" bit because the larger bit gives me about 1mm of free play in the trim tab as measured at the trailing edge of the trim tab. I contacted the factory and asked if this was OK and they said yes.
I used clip leads and a power supply to test the operation of the trim system. I adjusted the linkage to get as close as I could to +10deg/-40deg of tab movement. I ended up within 2deg of these limits.