I have had my Echo SRM 2400 for almost 8 years now. I strip the thing down every year [in January] to clean out debris and lubricate the drive shaft. Several other things that I do to make weeding my 3+ acres a lot easier...
First, when I load my .095" "string", I use 30' instead of the manual-recommended 40'. It puts a lot less tension on the wound string in the spool making the string a lot easier to come out, so very few jams.
Secondly, over 3 acres is a lot of weeding and my right index finger gets very tired depressing the gas trigger hour-after-hour. So, I got an
8" piece of VELCRO [the self-adhesive kind] and glued it around the the long drive shaft bar, just above the trigger. Another strip of 5" VELCRO is glued back to back, with a small loop at the bottom, that just goes around the trigger. When I start the whip, I fasten the "trigger loop" around the VELCRO that I have glued to the drive shaft bar.Just an easy pull on the VELCRO "trigger" until I attain the speed I want, join the 2 faces of VELCRO together and I don't need to touch the trigger again until I run outta gas... ;-)
Lastly, everyone has the same problem of the bottom "bumper" on the spool eroding away from repetitious bumps to advance the line. I have found a way to avoid buying a whole new spool, for a lot less than the $25 it costs.
Go to Home Depot or Lowe's or your local hardware store where they sell PVC pipe. Get a white, threaded, 1 1/2" PVC pipe cap. The next step takes a little doing!
You've gotta thread that cap over the bumper. What I did was slowly file all around that bumper to decrease its diameter, to conform to the thread on the inside of the pipe cap. Not too loose, though! Once you're close, if you have a wooden cabinetmaker's hand-screw clamp or a vise, you can compress the cap to the spool bottom.
You have to be very careful about judging the diameters!! If you compress the bumper too much, you'll bind the spool inside and prevent the string from coming out!
However, once you have done this and got it right, you'll never have to buy another string spool...until the little molded loop [on the inside of the spool] breaks down! Mine is at least 3 years away from that eventuality.
Let me know how well you make out and if I can help you more, I will.
All The Best!
Alan