OK, you previously said you had a 522 flasher, and now say its a 552. A 552 is a simple thermal type flasher. It will only work if you have 27 watt bulbs (#1156). If your new turn signals are something smaller in wattage, then they will not flash.
Most tree prong flashers from a parts store won't be a plug and play set up. Some have had luck adding more wiring to get them to work. Your 552 is a two prong flasher, correct? If so plug it into the stock flasher plug so it bridges the brown wire and the brown/white wire. The brown is power into the flasher, the brown/white is power out to the switch.
If your bike had the self canceler unit, the two prong flasher bypasses this feature.
On your new turn signals, is the bulb a single element bulb or a dual element bulb? If the bulb has two elements then the red and black wires may not be hot and ground, they may both be hot and ground through the body of the turn signal.
These with two elements are designed to have the turn signal on the brighter element and a running light on the dimmer element.
I have some of these to try on my 75. I like the idea of having a two element bulb. The extra lighting helps makes you more visible to traffic.
Just open on of your turns up and look at the bulb. If will have a silver dot on the base, one dot is a single element bulb, two dots is the dual. You should be able to see the elements inside the bulb as well.
Leo
As I mentioned in post #41, the 552 flasher will not work with bulbs smaller than 27 watts. You say you have 10 watt bulbs, so the 10 watt bulbs are not going to work with that flasher. You can either go back to stock 27 watt bulbs, or you can buy a flasher unit that will work with 10 watt bulbs.
With the switch opened up, check for voltage on the dark green and dark brown when you select left or right. Select left , should have 12 volts on the dark brown. Select right should have 12 volts on the dark green. If no voltage seen, go check the flasher unit, for voltage at the brown white wire, when the key is turned on.
Set your OHM meter to the lowest setting, remove a bulb, touch one probe to the metal outside of that light socket and the other probe to the battery - negative, You should get a VERY low number on the OHM meter if the socket is grounded well, do this at every turn signal socket.
It's still looking like you have a bad flasher, or a flasher that does not work with your bulbs, if you get an electronic one there would be no further question about the flasher.
Scott
It appears that the turn signal switch is defective.