I have a stihl fs 90r trimmer and i hate the head on it. its hard for it to unwind when you bump it. plus i hate taking the thing apart when i need to reload the string. I purchased the speed feed universal head thinking that it would work and go on just fine. but after numerous hours and taking it to my mechanic...i've found that its not made for my trimmer. What do you guys like to use in regards to trimmers and heads? should i ditch my stihl trimmer and go with a redmax or echo? Thoughts?