Hi @robclack ,
Don’t know the camera but here’s the [https://www.commentreparer.com/doc/8301/DMC-FZ35-FZ38.pdf|service manual] that may help.
On p.22 it shows how to view the error code history. Using this you can work out if the zoom lens has caused any error codes and what they mean. (see Attribute - Lens, Sub item - Zoom on p.23).
On p.29 there is the dis-assembly flowchart and on p.36 it shows the zoom motor unit.