I had a nice trimming opportunity to do "when you have some time when the season winds down." I knew the job would require two full work days, over 50 burning bushes, 25 Canadian Hemlocks to shear, plus some other bushes. The weather was cold (35-38) on Friday, but I decided to start. I used my Stihl HS-80 nearly all day, getting most of the burning bushes trimmed down. We made good progress despite the heavy dress and cold temps. The trimmer worked flawlessly. On Saturday morning, the temps were colder, about 25 at 8:00, but forecast ed to warm up. I use my Stihl FS85 string trimmer with a zero-degree hedge clipper attachment to shear the Canadian Hemlock (9-12 ft high, 7-8 feet across at the bottom). I mounted the attachment on the FS85, but the cold gear case made blade movement difficult. The engine was revving, but little blade movement. I realized I was slipping the centrifugal clutch. I took the unit inside the house, running hot water over the gear case to warm it. When I took it outside, the engine was able to drive the clipper pretty well. However, I could tell the engine was really laboring to drive the blades. I used it a few times this Summer, and it worked fine. When getting to the job site, I fired it up right away, hoping the gear case still had some heat (normally, it runs quite warm during service). It worked, but I always felt the operation was a bit erratic. The engine was under heavy load, not from the shearing operation, but just to keep the blades moving when the temps were cold. I trimmed about 20 of the Canadian Hemlocks, running through 3 or 4 tanks of fuel. But, I'm concerned I may have damaged the clutch. Is there any way of knowing? At the end of the day, when I got home, I changed the clipper attachment back to the string trimmer. It fired, and run well. The trimmer is about four years old, trimming out 1,000 to 1,200 lawns per season. I don't want to start a new season, if I have a marginal clutch. Any way to know if it is OK, short of pulling it apart. P.S. The hedge clipper attachment for the FS85 is a huge time/energy saver on these jobs. It has paid for itself several times over in the past couple of years. I only needed a ladder on one tree to finish out the top, the rest of the work was all done from the ground. I needed about 15 minutes per tree, including all cleanup.