Hi the back is MDF that's why it takes water really easy and the sides are Plywood ,they should make the back the same but they don't ,it's not easy too do but it's best too change the back but fixing what u got I guess take out what's lose and fill with wood filler or something like that it might take a few times too do so put some wood on the bottom too fill the bottom too get a nice corners ether way it's a lot of work

Ya it looks like and it's so hard too fix MDF ,I had the same thing as u but my was the bottom of the main Cab it's also MDF and it was too far gone so I changed the hole bottom and it was the same as the back of the head just bigger lol I just took my time cut it out and took out the little wood that fits in the sides then cut out the bottom too fit in the new one the made up little wood clue them in after the bottom was in filled sand wouldn't know

Part of me says to use wet wood glue and squeeze clamp the back together.
Then, when dry, to go back and route out the bad stuff and cut fresh mdf to fill
in as much as possible then use wood filler etc.
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Or, cut a hole new back piece and replace.

Yes MDF most times is hard too fix when it's that bad when water gets too it that bad it goes right though it and just comes apart hard too fill and make it look likes it was fixed that's what happen too a bottom of the cab I did it really wasn't worth fixing so I did a full change out with a new one wasn't easy but can be done and looks was better if u don't mind the time it takes too do so

Yes just take your time the sides of the head are plywood so they are strong just like I did with the bottom Cab it also had the slots on all 4 sides so I had too cut out 3 of the slots too get the new one in then I made up new little wood on the 3 sides and glue them back in now u would never know it was ever done ,I have never done the head but I think there's only 3 slots and the bottom is nailed there not sure check it out if so it should be easier too get the new one back in

Yes. Just take your time. The sides of the head are plywood, so they are strong. Just like I did with the bottom Cab. It also had the slots on all 4 sides, so I had to cut out 3 of the slots to get the new one in. Then I made up new little wood on the 3 sides and glued them back in. Now you would never know it was ever done. I have never done the head, but I think there are only 3 slots and the bottom is nailed there. I'm not sure, so check it out. If so, it should be easier to get the new one back in.

I'm sorry, but that was making my head hurt.

Great work yes it does take time but it's the best way ,it's easier then doing the bottom of the cab that's for sure ,keep us updated when u have time

That's great it's all about taking your time and anyone can do it if u want too great start

Hi nice what wood are u using MDF or plywood good on both sides

Very very nice great job see not as bad as you first thought way too go

Bravo!

Yes for sure nice too have the right tools for sure well great job bud looks great way better too go new

WOW! Great work!!

Great work almost like it was never done