I had a 1680 and a 1688 and a 480 Lexion. The first failed rubber bushing happened at 15?? on all of them. I just changed them all when at it. I changed the bearings on the shaker drive while everything was apart also. I do not know for sure, but a magic number seems to be about 1500 hrs in my experience. You are due!!My 2366 has about 1800 sep hrs. how soon will I need to change the bushings on the sieve shaker arms? everything appears to be fine now.