I had the same symptoms with my S7 spider failure. I initially noticed occasional high beam indicator coming on even though I was running with low beams and I also had occasional split second drops in engine power (like someone switched the engine off and back on very quickly), but those don't sound like your running like crap problem. It progressed to occasionally not starting and finally hard headlight failure. When the headlights died at night near my home, I had dim turn signal indications on the dash and also high beam indicator light on the dash.
Spider S7 is above the left headlight and S8 is above the right headlight. I wish I had saved the post, but someone had posted how to remove the whole nose assembly (headlights/dash/windshield and all plastic) which is what I did. It's not that difficult -requiring removal of both side fairings, disconnecting all connectors leading to front cowl and then removing 2 bolts in front of steering that then allow the whole assembly to be lifted off the bike. Once on the bench, it allows access to the 2 spiders.
I've started a thread to track failures of spiders other than the recalled S4
HERE . There's also a link to my original failure in that thread.
