My 3 position Gravity Dropper classic isn’t functioning correctly – Only the top or bottom positions will engage not both. If I loosen the top cap to get the top position the pin will not engage in the bottom hole. If I tighten the top cap I can then get the post down into the bottom position but the pin will not locate in the bottom whole to get the top position.
I’ve taken it apart and there appears to be no problems and I’ve email Gravity Dropper who couldn’t suggest anything other than return to US for service.
Before I send it back does anyone have any suggestions as it’s a mystery to me why it’s not working?

Can you remove the spring and then put the top shaft back in to see if it will lockin in all postions?
Sending it back to the US for that would be costly.

Strip and clean the whole thing down and rebuild it.

I had a similar problem try taken out out the post and with a small file or blade of a screwdriver just open up the hole a tiny bit as I think the edges can get a bit out of shape and stop the pin locating,it worked for me.

yes what they said
Spring out and test the post
Cable off test the post
Post off and locator pin off post – do they fit?
Check alignment when in the GD
Make holes bigger if you think this will solve but it may invalidate any warranty
If you are North west based I can take a look
Make holes big enough if there is an issue

Cheers for the suggestions, I had already filed the edge of the top hole slightly but it didn’t help. I think the problem is actually with the lower hole (post fully up) as to get it to engage the top cap is unwound quite a bit. The fact that the post won’t go into the lowest position is because the top cap is unwound so far it stop the post sliding down any further.
I’ll strip it completely tomorrow after my ride.

I stripped it today apart from removing the shims and I still can’t get it to work.
I guess I’ll have to send it back

When you say tighten the top cap have you fine tuned how tight the collar is rather than just winding it right down? Mine wouldn’t engage after a service, but it turned out I’d over tightened the collar. Backing it off 1/8 to 1/4 turn got it back to full function.

If I back it off enough for the up position to work the pin wont then engage the post in the down position. The top cap looks out along way when the up position works so I think it’s a problem with the up. The post is so simple so it’s very frustrating that I can’t fix it.

My mates was doing this, turned out to be just wear and tear on the post- he’d been riding for a year with it full of grit and ignored the scraping and rattling, so the seattube was so worn it wasn’t moving freely. But I think you’d have spotted that from the sound of it…