Older Hesston 100-90 Seat Removal ?

Hello, and thanks for any consideration. I have been working on a small 60 acre vineyard in California whose only tractor is a older Hesston 100-90. Used it with no issues last season, mostly mowing between rows etc. The seat is a disaster, and the penny pinching owner of the vineyard finally took pity on my vain attempts at using tape to keep it together and told me they would get it reupholstered if I could get the seat out. The seat is a Grammer DS85H/3A which is every bit as old as the rest of the tractor, and for the life of me I can't figure out how to remove the seat pan/back short of taking the entire assembly out. I would have thought that the lever for the slide would allow it to come forward, maybe with a screwdriver assist, but it doesn't appear so. Does anyone have a clue how to remove this seat without taking most of the interior out? Replacing the clutch, no problem, fixing numerous mechanical issues, easy peasy, removing a seat, I'm stumped. Thanks for any help.

Hi I hate working on tractor seats in Cabs, The last Grammer one I did was in our Valtra cab thats a lot bigger than that Fiat cab to work in. I
just take out the 4 mounting bolts on the floor and get the whole seat out so it can be worked on easily. There are several types of Grammer tops.
some have metal turn buckles holding the back and base cushions like my Belarus has. My Valtra has a few small screws holding them along one edge
and some plastic locating pins that slot in to the metal frame so you don't take the seat frame out to replace them.

I'm thinking the seat you have might be one with a cloth back covering where you can't see the main frame/ pan like a car seat construction, or
it's one of those vinyl covered ones. I can't remember if they have a bolt or 2 somewhere in the rails that stops the seat coming to far forward you
need to remove, i know the rail to seat suspension base bolts are a pain to undo on both mine.

My thoughts are if the seats that bad why not take the whole thing out probably spend a couple hundred more than the upholstering would cost and
put a new seat and suspension unit in. Those bases wear out and get pretty loose. The last one I did on my Valtra one of the springs broke and all
the bushes were worn. It's a real nice tractor to drive now the seats tight and it's not squeaking on every bump. I should of done it 2000 hours
before it broke. There are some real nice units available online to replace it, even if you just did the seat would probably be cheaper than fixing
yours.
Regards Robert

Thanks for the reply. Yea, if it were my tractor I would replace the entire seat. Unfortunately the owner is often penny wise and pound foolish in most things. The bolts holding the seat to the rails are very tough to get at, especially the ones in the rear. You need to remove the plastic covering the bottom to make enough room. Same with the stops on the rails, need to remove the seat to remove the stops. Obviously it wasn't a mechanic who designed it. Should have been very simple... Thanks again