OK, thank you for your reply.
No, it can't help.
I have read the switch motor manual (more than once) before trying to install it.
I have posted this question because the manual does NOT help to solve the problem that I have reported.
Actually, it seems that the 9 lever (which manual tells to use with Peco turnouts) is just not suitable with Peco turnouts... or can you explain how ?
Thanks in advance for your reply.