Gear Help

Nearly all pictures are from the top a few from the sides are needed with angles etc

Hey,
I took some more pictures. Let me know if this helps. If you need me to take more, I have no problem!

Thanks!

My best guess is attached.
I believe more, and more accurate dimensions are needed to make a "perfect replacement".
But, if this is being printed, then the end results are likely going to be disappointing when compared to an injection molded part.

I left off the material saving features since this is not being injection molded. Plus there is a good chance that the dimensions are off somewhere, so no sense in spending a lot of time on the smaller details, at least until the major features are a match.

Do you have another non-broken gear?
3D printing via an FDM machine is almost certainly not going to work well. If the "real" acetyl (guessing based on appearance) gear broke, an FDM option is not going to last long.
For a longer lasting fix, consider some other options:
1. Create a soft silicone mold of an existing good gear. Then cast a few duplicates in a durable urethane material with properties close to the existing material. It won't be an exact match, but it will be better than "plastic".

2. If the gear an be accurately defined, it is most likely a common off the shelf part. Chair manufacturers would not look to reinvent the gear when making a chair. The chair maker may be out of business, but gears are still available from multiple sources.

3. Consider having the part made from a more durable (and accurate) 3D printing material and method. SLA, SLS, and DMLS will all cost more than FDM, but the quality of the part and material properties will also be better.

26 teeth seems to be a bit of an oddball size. You might consider replacing both gears at once with a 24 or 25 tooth option. They are more common, and should cost less.