About six weeks ago, I bought a new commercial 21" LB SP to use in place of a Toro commercial (5.5 Sizuki). I posted a note about this change. After six weeks (about 30 gallons of mixed fuel, maybe 250 hours of work), some observations: 1. The change was the right thing to do. The side-bagging LB works so much better in our environment. Heavy clippings, damp, wet, whatever ... the debris ends up in the bag, not the chute. 2. The results of the mowing are very good. We've gotten compliments on our work. This was not a surprise because I had used an older LB, which we still use periodically. 3. The Dura-Force engine is very efficient, running for perhaps 8 hours on a tank of fuel. Only a few times have we run it out during the course of a day. 4. The quality of machine is very poor compared to the Toro, as a piece of equipment. A few items: a. The rear drive wheels have already lost about 70% of the tread. They will need replacing in another four weeks. b. The side bags had holes in the bottom after two weeks. I use two bags from the new machine, and two from my old LB, so the bags weren't being used full time. This is no real problem -- the old bags have had holes for a long time, and still work. c. My biggest complaint is the Dura-Force engine. The Sizuki engine works like a fine-tuned instrument, compared to the flaky Dura-Force engine. The notion of "one pull" start is a joke! This is not only true for a cold engine, but also for a warm start (trailering to the next job), or even a hot start (changing bags). The engine pulses at times, not always, and not predictable. This happens with a cycle of perhaps five seconds, faster, then slower, then faster, then slower. The power is OK, and the engine continues to run to get the jobs done. But, after living with the Suzuki for two seasons, I am less than impressed with the Dura-Force engine. My old LB is a model sold just before the Dura-Force was on the market (1998?). It has been used heavily over the years (5,000 lawns?), and it runs better, starts easier and more consistently, than the new one. Yes, it makes more noise, and yes, it has had many parts replaced, but the engine runs like a champ (100:1 Amsoil). I have tried the same Amsoil mix in the Dura-Force, but returned to 32:1 LB oil. I've read some threads where 50:1 Stihl has been used in Dura-Force, ... maybe I'll try a couple of tanks of that mix. I use 50:1 Stihl in all my Stihl hand tools this season. Anybody have any suggestions to make the Dura-Force run better? Thanks. P.S. I did return it to the dealer and their word, "... this is the way they run." I don't believe that, but don't know what else to do.