Guys, thanks for your replies
No, not rushing it, and it's intermittent problem that seems to occur after parking for a while and needing to reverse out of parking space. Not had it when maneuvering into space after driving.
Tried putting it into 2nd as well, pressing clutch several times no difference (this used to solve the issue on my old mx5)
reset clutch pedal auto adjust sounds like best thing to try first
re 10W40 in a gearbox - JamesBryan, glad this made you laugh - unless those were tears of despair?
Can't find anything online about it so phoned Gearlink in Salisbury and the guy I spoke to confirmed I'm not insane (well on this issue anyway) and 10w40 is common choice among transmission specialists esp on recon boxes! He said they select a lubricant most suited to the synchros in a specific box rather than blindly go with manufacturer recommended fluid - but they don't like to tell people outside the trade this because they often get a horrified response 😂
I'm pretty sure this is exactly what a certain well know Renault specialist put in my previous 182 after I complained about beating the synchro into 3rd and I never had it crunch again after they did it...
Should add that the fella from Gearlink reckons my crunch into reverse is clutch related as SteveM suggests so won't be doing a fluid change yet
Anyway, now I've thrown the cat among the pigeons I'll restate my question - anyone on here heard of putting 10w40 in a gearbox?!