NormK,
These whipper snippers (string trimmers to me) are not as bad as you think once you get hang of repairing them. Just apply what you know about 2 cycles to them. For me had learn on the fly with no basic knowledge of 2 cycles when I started; only had worked on 4 cycles before. Being patience is key to working on these.
What help me was time and a truck load of thrown away trimmers. I ended fixing nearly 3/4 of them and sold them. No great profit other than learning experience I received. No great lost other than my time and parts used during the learning process but being able to sell few sure didn't hurt. When I first start it could take me all day on what now is a simple 30 minute repair.
Just beware the replacement vs repair cost. If the repairs here exceeds 50% of the replacement cost then usually not worth fooling with. Other words those use it and throw away with broken trimmers are just that.
One thing to remember too is unlike other two cycles that you're familiar with you will at least 110 psi compression for one to start most times though I have seen a few that would start @ 95 psi. Even then they don't work very well.
