why did you think the old flasher was bad if it tests the same as the new one?
according to the tech tip, the black wire should go to a rear light, yellow should be the load wire from the flasher ...dug up the diagram I have from my bus 900 series unit [which has the socket letters that are missing from the tech tip] ....
shows X to power via fuse, L is yellow to sig unit, P is blue to pilot,
black & gray to rear lights, red & green to front lights ...
if X & P always have continuity the flasher [or socket] is bad, my 3 pin flasher [works fine] has continuity between X & L at rest, P has no continuity to anything at rest, it should get power when the flasher is active .... when the circuit is completed by a selection of the lever, the flasher opens the circuit to L, closes the circuit to P, clicks back and forth between them .... another thought, make sure the sig unit is grounded to the column via it's mounting
my flasher is a Tridon, standard 3 pin 12V mechanical flasher, only numbers on it are 3355C and HD-13
Bill