Left side of the flashes run slow.

[sida555]

Hi I have a small issue with the flashers. The 4 way flashers and the right side work in really good speed also the indicator on the dash lights up well. When I put the left turn signal the flasher runs a bit slow and the dash barely shows it's blinking. Outside lights are bright. I have checked and cleaned all grounds and connections on the 4 corners. Any thoughts ? It looks like the car has a heavy duty flasher under the dash. Probably not the original.

[spider2081]

I have checked and cleaned all grounds and connections on the 4 corners

Does that include removing the bulbs, cleaning them and their sockets before re installing them?
Sometimes the steering column contacts need cleaning and tightening. This is a tedious and time consuming repair. Many people opt to replace the entire assembly.
It is not uncommon for one side to be slightly more voltage sensitive then the other. Have you cleaned the battery terminals and fuse contacts?
An old timers electrical saying: "Clean and tight make all things right"