We used to have a fleet full of Smart Vectors and I have learned a few things about maintaining them (and rotators in general). Your problem is almost certainly the rotator post. To fix, remove bulb retaining clip, remove bulb, pull rotator body off. Then clean the rotator sleeve (the hole) with water and a mild detergent/degreaser (best in my opinion is
http://www.slip2000.com/725.html ) and dry. Next, clean the metal rotator post by wiping it off, degreasing and drying. Lightly lube the post with plastic-safe white lithium or similar. While you are in there, be sure to clean & lube gears, clean/polish reflectors, check wiring, and inspect the bulbs (if the filaments look stretched or "gritty" then just replace them preemptively.) This was my method for keeping the Smart Vectors running and it worked well. You will be amazed at how much noise the rotator post causes.