heres something to try. There might be an obstruction inside the speedo itself. Heres one thing I tried. I took the gauge cluster out of the dash, and I unhooked the drive cable for the speedo. THen, I got a nail, I cant remember what size it is, you will have to try different sizes. I cut the head off of it, and put it in my drill, with the sharp end sticking out. I put it inside the back of the speedo where the cable goes in, and turned it on. the drill has enough speed to test the speedoo, so it shouldnt be a problem. If your speedo still makes the ticking sound and the needle jumps, you have an obstruction in your speedo.
if you want to, take the speedo apart and check out the internal parts. Inside the speedo, there will be a bell shaped piece inside that connects to the needle. On the other end where the cable comes in, will be a two pronged fork like piece. If you take it apart, look for metal shavings, little bits of dirt, anything that will stick to the pronged piece, because it is magnetic. And, check to make sure the bell and the prong isnt bent, cause if they are they will hit each other and cause that clicking sound.
