I've talked quite a few times about my favorite models, of which there are many. I have my least favorite models too, which I don't talk about often but I have an opportunity to do now, sort of.
My least favorite watches are some of the funky and chunky examples from the mid-1950s like the 1954 Kenmore. That's not entirely fair though as when you pair the custom bracelets to them they really aren't that bad.
The set of models that I really don't like are the later addition micro-rotor movements in the TM-line of Thin-o-matics. That's unfortunate, as they aren't unattractive, they are just difficult to maintain, as you'll see in this post on the 1968 Thin-O-Matic TM-2601.
The TM-2601 was made through 1971. The micro-rotor movements used in Hamilton's Thin-o-matic line were made by Buren, which Hamilton purchased in the 1960s. In 1969 Hamilton moved production from their Lancaster, PA factory to Buren's factory in Berne, Switzerland... and the servant became the master.
Microrotor movements come in two flavors... pink and silver. The pink calibers were the initial movements introduced in the late 1950s and used throughout the 1960s. In the late 1960s the 2nd generation silver microrotors were introduced. They're easy to identify as they are comprise the TM-line of models. With a date complication they would be Dateline TM-models.
The TM movements were not produced for very long and they were also used in high end watches like Breitling. Spare parts have long been exhausted so when you need parts you're likely out of luck and will need to scavenge from donor movements.
The TM-2601 has a solid 14K gold case, thus the 2-series designation. Based on the catalog image it originally came with a croc or alligator strap. The bezel is reeded, like the edge of a coin. It's a very striking watch. The catalog indicates it came in yellow gold but I've seen an example in white gold as well.