G'day lads, here's a Carbontex upgrade (courtesy of Dawn at Smooth Drag) for the Shimano 400.
I just found Alan's tutorial for the 400, but seeing as I've already taken the photos etc, I figured I'd post it anyway.
I'll be sure to do something new next time!

Righto, off we go...
The 400 is a cracker little reel, despite not having an anti-reverse dog.
This one was thrown out by a customer who'd fished it for a few years, lost most of the internals and eventually given up on it.
I replaced what was missing and restored the rest, and have caught some great fish on it since - including all the snapper in a previous post.

First up, loosen the two side plate bolts - I generally keep them firmly finger tight, perhaps with just a little tweak to finish 'em off.
Pull the spool and and loosen off the handle nut cover..

Loosen the handle nut and check for the friction washer, which will usually be stuck to the bottom of the handle.

Remove the star drag and check for the star drag spacer, which (once again) will usually be stuck to the bottom of the star.

Remove the drag spring washers (bellevilles) - there are a number of configurations, but generally they'll be two thick (), beneath two thin ().
Remove the two screws and lift off the side plate - the anti-reverse bearing can now be pushed out of the side plate, along with the roller clutch inner tube.

The main gear may not slide easily off the drive shaft, so remove the top drag washers.

You should eventually be able to slide the main gear off...

Slide off the the last drag washer and the anti-reverse ratchet.
This is what it all looks like once removed...

Here are the new Carbontex washers and the old Dartanium versions.
Apply Cal's to the new fiber washers and reassemble as per the following pics...

The main gear goes down next, followed by the washer with the largest ID.

Steel drag washer (keyed, no ears) next, followed by greased fiber (the remaining two are identical).

Eared washer next, followed by the last greased fiber washer.

The last keyed steel washer goes down next, followed by the roller clutch inner tube.
Apply a little Cal's grease to the tube internal (a good idea of Alan's)...

Slide the tube down the drive shaft and position the tube keys in the keyed washer.
Reinsert the anti-reverse bearing into the side plate.

Position the side plate on the set plate and replace the screws.

Replace the spool and carefully align the spline with the pinion gear.
You'll need to slide the 'Quickfire clutch' (ie thumb cast control) upwards to align with the clutch plate.

Nearly there now... Tighten the two side plate bolts and replace the two thick bellevilles.

Replace the two thin bellevilles so the final configuration is ()() and be sure to apply a light coating of grease to each one as you go.
I use a slightly larger star drag spacer on my 400.

Replace the star drag and apply a little grease to the contact patch of the friction washer.

A little grease on the handle, where it touches the friction washer...

...reattach the handle and handle nut plate...

And just like that, you're done!

Hope that's of some value.
All the best, Justin