Key not going all the way in to ignition lock barrel

[King Key]

A lot less messy than graphite, excess ACF50 or GT85 drains away, graphite doesn't.

 

[MattW]

I've used a 'dry slide' lubricant in locks before (in fact I use it for all sorts, it's ace). It's molybdenum particles in a solvent carrier which evaporates. I bought it for guns (auto's especially) they don't like sticky goo gumming things up. It works best if you can spray a couple of coats on and burnish it into the metal, with a final coat unburnished (I used to do this on my 1100 gearbox and drive shaft splines before lubing them). Obviously you can't burnish the internals of a lock but I squirt brake cleaner in there to blast out any crud, let the brake cleaner evaporate with the lock flap wedged open with a match and then a quick squirt of dry slide (again wedging the lock flap open to allow the solvent to evaporate).

Works a treat.

 

[Tallguy]

Update: it turns out that the very tip of the key was very slightly twisted. So in the end it wasn't lubrication that was needed (though it helped). It needed a slight un-twist careful not to fatigue the metal too much, then I swapped to the spare key for now.
So thank you all for your suggestions, and my first check next time will be the key tip!

 

[Bendy toy]

Take care how you open the seat lock.

 

[Delboy777]

Clean out with WD40 then using your key open the slid and squirt some 3 in 1 oil down the barrel.....................sorted.