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Welcome! You have come to the right place. A lot of good, helpful and knowledgeable folks here. Frankly, they have helped me a lot with my 550.
Also, there is a lot of helpful info if you will search any subject/problem.
From what I have learned here, may I make a couple of suggestions? (You likely already know about these things and may have already done 'em.)
1. Clean your fuse clips - a .22 caliber bore brush works perfectly. The clips may just look a bit dull but they should be bright and clean (ask me how I know). Make sure the clips grip the fuses very tightly (may have to carefully squeeze 'em a bit).
2. Run a "Popwood Ground" by splicing into only one of the green wires soldered to the large headlight retaining nuts inside the headlight bucket. Run this new ground wire to a coil mounting bolt using a ring terminal. Clean the frame to bright metal where the ring connector touches the frame. Then, you wont have to hunt and clean each and every ground connection on the bike. This may correct your turn sig/headlight problem - of course, it could be some other problem.
3. Clean ALL "gang" electrical connectors in those poly housings (including the one on the ignition switch) and the pack 'em with dielectric grease (to help prevent more corrosion).
These things fixed my problems (similar to yours). Til I was told on this Forum to do these things, my 550 was absolutely usless!
The wiring on these ol' bikes accumulate lots of corrosion over the years that causes a lot of elecrtical problems. These simple things can prevent a lot of problems for you (if they haven't already been done).
Good luck with your 550.
Gaither