I've got everything I need as far as tools, or at least I think I do.

Here's what I've done so far.
1-removed rocker arm bracket and ball sockets came right out.
2-Have cylinder pressurized to 5 bar per workshop manual.
3-compressed spring with KD tool.
4-tapped valve spring plates with a very small brass hammer to try to get valve collet halfs to detach. No luck with that So I need to determine what to do next.

I wonder if I'm not hitting them hard enough or if I'm not depressing the valve spring enough.

How many coils on the spring should the compresser have between the top and bottom part of the compressor? What might I be doing wrong?

Edited:
I think I did not have the cam positioned properly for cylinder #1.

With the cam lobe for the exhaust valve pointing straight down, I believe that is TDC for cylinder #1, the cylinder pressurized when I introduced 5 bar pressure. The ratchet I used to turn the cranked moved slightly and lodged against the pulley belts holding it in place. I believe this is correct.

I’ll depress the valve springs tomorrow and set if the valves move upwards so I can remove the collet halfs and install the new seals.

Does that sound like the way to proceed?