Tissot have changed the serial numbering system on their watches twice so you may have a few options returned, other details of the watch and logo may be used to narrow it down. The Tissot serial number formats supported by this tool are numbers only (no letters) and between 1 and 7 digits long. I am still learning about the Tissot formats that contain letters but as far as I can see the serial numbers on the movement itself will be numbers only.
As Tissot abandoned serial numbers in 1984, after that date other methods will have to be used to date the watch.
You can find your serial number either engraved on the movement or on the inside or outside of the case back.
Tissot Serial number :
Click herefor an idea of what it may be worth (via previously sold items on eBay)