How to attach bowden tubing to other side of extruder?
There are several ways to mount a PTFE tubing to the extruder's feeding side.

Connector solution

You'll need a pair of PTFE tubing couplers, a length of PTFE tubing and tapping tools for the mounting, and the lever should be metal:


Disassemble the extruder
Take the intake side lever
open up the intake hole to your PTFE tube connector's inner diameter (that is the diameter, where you cut the thread from!)
tap the hole
screw in PTFE coupler
connect to intake tube
Repeat 3 to 6 for the drybox side, possibly add a nut from the inside
Feed filament through the tube


If you have a plastic side, it reads like this, and you will need an insert that fits your adapter's screw:


Disassemble the extruder
Take the intake side lever
open up the intake hole to a bit under your insert's outer diameter
use a soldering iron to melt the insert into the lever
screw in PTFE coupler
connect to intake tube
Repeat 3 to 6 for the drybox side
Feed filament through the tube


free "inner" side

Instead of using 2 connectors on either end of the tube, the one on the extruder can just be "slid" into the block and then fastened.


disassemble the extruder
take the intake side lever
drill open till the PTFE tube can slide in snugly into its rest position against an inner ledge.


For REALLY hygroscopic material, drill through
drill a side-hole and use a small screw to fasten the tube in place
alternatively, use hot glue on the outside and secure the tube.