actually... pls dont mention your fuel manufacturer. I dont want to start another pissing contest. Please try another brand of fuel. I suggest this because I believe those deposits on your case are parafins- i.e. cheap wax lubricants. Your fuel should not be leaving reddish brown deposits on your case like that. The surfaces of the case ports are actually honed (super smooth), which makes it difficult for most anything to stick.

Again, please try another brand of fuel.