Hi folks, probably a bit late to this conversation but about a month after buying a second hand Xfusion manic 150mm dropper seat post it started to play up, it wouldn't go up properly, i stripped it down to discover it was full of gunk...i cleaned and put back together, worked a treat for about a month and stripped down and it was the same again, inspected the cartridge and it wasn't working right and leaking oil.looked on the internet to see if i could get a replacement easy but no. i spoke to a guy at Xfusion and there was 2 places in Europe where you could get the part one in England and one in German. After getting in touch with the company in England who deal with Xfusion stuff and servicing they told me i had to send the dropper to them,i sent back to say i only needed the cartridge but they said no , i had to send the dropper to them, he also said that the company in Germany would probably be the same about this. After looking about on the net to find a similar looking cartridge i found this
GiantContact&ContactSSwitchDropperSeatpostReplacementCartridge(15000007)-440mm|#0.00#|PartCode:150000077 £34.99 1 £34.99
Bought it from the cyclestore.co.uk and it fits perfect and works the same as the original there is a slight difference in length on the thread at the part where the seat goes that is fixed to the post with a locking nut, i put thread lock on this part and all working fine.