After reading the excellent reviews, I eagerly purchased the Pack Of 6 BlueStars Ultra Durable Primer Bulbs (BlueStars) for my STIHL FS36 FS40 FS44 Trimmers, Echo CS300 CS301 CS305 CS306 CS340, and Poulan PP445 PP446. The promised "exact fit" seemed like a dream come true for my DIY efforts, but unfortunately, my experience fell short. While the bulbs were indeed durable and well-made, the "exact fit" claim was a bit of a stretch. While they fit on most of the models I tried, they did not workโฆ