some thoughts
rack damper has had too many shims removed to reduce free play
has a repro modern UJ been fitted in the column and its seized
lack of oil in the trunnions use ep 90 never use grease
lack of grease in the rack (may need a nipple fitted)
low tyre pressures modern tyres need more than the manual PSI add 4 to 6 psi extraa squirt of lube in the top column bush should solve the squeal
the cancelling can be failed switch ,the clip on the column is located by a dimple, so its not really movable the column may be mispositioned on the UJ or rack to set the lug on the clip to 3 oclock
Pete