https://www.repco.com.au/globes-batteries-electrical/electrical-accessories/flashers-relays/oex-glow-plug-timer-12v-universal-acx4870/p/A5413729?kwSearch=glow%20plug%20timer
This is one step up from the wilson switch. I have used this on the diesel engine in my boat for many years as a...
You just can't just fit a valve from another engine into what is a damaged seat. It is doomed to failure and will have to be pulled off again. Do it once and do it right.
No 1 inlet valve is not seating properly. It could be seized in the guide, which would bend the pushrod.
Also the pushrod could have fallen out of the rocker or lifter and get bent.
https://www.ebay.com.au/itm/183738448795?epid=561988077&hash=item2ac7aa3b9b:g:sEUAAOSwn8dhzJlQ
This is the one I have had on my turbo 2H for many years now with no problems.
Easy to fine tune boost from inside the cab while on the road.
Just had a thought.
If you could take a few thou off the front face of the 5th gear engagement dog on the end of the counter shaft.
That should cure the problem.
Could easily be done in a lathe.
I would be very surprised if the was any change in the 5th gear end of the counter shaft components from 87 on.
TT seems to think there is no upgraded parts.