Tektronix 434 s/n below 500000 faulty ps.

[Craig]

If I turn the Timebase cal knob fully clockwise or anti clockwise nothing happens to the waveform. The pot does nothing.

Which Timebase cal knob is this?

Craig I am really sorry for asking all these questions I have watched many oscilloscope videos and tutorials but its like learning to drive you can read and listen but nothing beats practicle experience and making mistakes which I am trying my best to avoid with this scope due to rarity of parts.
See photo's when timebase set to 0.1m/S should each gradient have a signal?

You are pointing to the Variable Time/div knob. This has nothing to do with triggering

The shaft that connects the knob to the variable control (R799 diagram 8) has the knob screwed on at one end with a grub screw (which you have already tightened), and at the other end is secured to the control with another screw. That screw might be loose, so the knob and shaft rotates but the shaft just spins uselessly in R799. See if you can find the screw on that control and tighten it.

Craig