TD4 Auto - Starter Motor Replacement Solenoid Contacts Life

I'm wondering what people's experiences are having replaced the solenoid contacts? I did mine a couple of years ago and all has been well. Recently though when starting the car, on three or four occasions it's not turned over.I first thought it was something to do with gear selection sensor(?) as I thought that it couldn't be the contacts already! and the car must think it's not in neutral or park etc. But then I wondered if the replacement contacts have a shorter life than the originals. Any thoughts?

After turning the key a few times it's fired up. I'll be looking at earthing and the ignition switch next I guess. The battery is only a couple of months old and is in tip top nick.

Mine are fine, although they've only be in a year or so.

I don't think the replacements have a shorter life, but I guess it will depend on the quality of the copper used.