Please help me identify this Tissot model

Hello @MrRightWatch and welcome to the forum!

You have a lovely heirloom: It is a stainless-steel Tissot caliber 28.9 chronograph containing Lemania's 13CH movement inside. Based on the serial number, your watch was manufactured around 1940. The dial numbers and hands on your watch were designed to glow in the dark (luminescence) using radium, which still has some radioactivity today contained within the watch. You do not need to open your watch.

The watch is a screwback model with oversize pushers - back in the day these models were promoted as water-resistant watches, although that water resistance has long ago been lost to time so care must be taken to avoid moisture. As seen in this catalog image, the watch was Reference 6156, although that reference would have had several other dial and hand variations in addition to yours:

If you intend to wear the watch, you'll need to find an independent watchmaker who is familiar with working on vintage mechanical chronographs and ask them for a full service. They will carefully disassemble the watch, check the parts for wear and tear, clean and lubricate the parts, and reassemble the watch for you. The collectors on this forum generally recommend to avoid polishing the case exterior, as this process removes the crisp edges and shadow lines that define the case design. A light cleaning (no liquids) of the case is all that is needed.

Hope that helps!

Thanks for calling me, but I think @Vitezi is the real expert on these...as he has proven again 😀

Wonderful watch!