[Frank Miller]

I guess if one understands how a flasher works it is easier to deal with. It is no more than two strips of metal fused together with different expansion rates. This bi metallic strip when heated becones curved and breaks the connection. No current flow then no heat and it straightens out and completes the connection causing it to heat up again. If there is too much current which you get from more or brighter bulbs it will cycle faster. Too little from LEDs or a burned out bulb and it will not work at all.
That being said figure out how to reduce the load on your system. Either remove excessive bulbs or use bulbs requiring less current.