G7167, 1290 MLS

I have a 1290 MLS, G7167 multi-sampler that will intermittently stop in the middle if the SS/run. The sample tray usually gets stuck inside the chamber and will not return the sample tray or the needle will get stuck in the vial. I have firmware 7.20 installed, lubricated the transport assembly and replaced needle/needle seat. Any suggestions? Can the transport assembly be replaced? Thanks for any feedback.

Scott