Checked the wheel bearings and steering head bearings, all fine.
Push down on suspension and it compresses nicely. If you pull up on suspension, returns part way but not fully to normal sitting position. Apply a little pressure and down she pops. Feels as though there is a slight area where there is just no damping on the forks.
Thing is, now the weather has warmed up the jolt when going over bumps has completely disappeared and all feels fine whilst riding, still does the same if pulling up on the suspension though.
Could be as simple as low fork oil? or something worse. (and yes i know, the best way to find out would be to take them apart, but I'm trying to guess what it is before I attempt that
)