speedometer bounces?

Yep. The speedo cable turns a 90 degree curve through one little strap under the driver seat. Thats where they normally wear into the housing. Most cases they make a noise.
I disconnect the cable at the trans end and let it hang down then disconnect the instrument end and pull it down and out to below dash. You'll likely need to move the fuse box to gain access. I grab the cable with pliers and pull it out of the housing. Flush the housing and the cable with brake cleaner and compressed air. Then I lube the cable with white lithium grease while re inserting.
If that doesn't cure it you'll need a new one.