Further investigations: it seems to be mechanical.
The hooked lever that pushes into the switch doesn’t engage enough at first LIFT button actuation to click in place and keep the platter running. At second actuation it fully clicks in and the starting process goes as it has to.
I’ve cleaned it again but I wonder if it’s not related with the rod pushing that lever from the LIFT switch. But I see no adjustment and that rod looks so fragile…
Any idea please ?