The gears are nylon (polyester) on your machine, and the buttonholer will not damage them. The strain is as you mention mostly on the needle clamp and you will notice of the machine works too hard. Singer made buttonholers most of the 70s for the new models too, if not longer. The later buttonholers were a bit different than your 160506, but generally worked much in the same way. Make sure it's oiled (take the black cover off) and that all parts are moving nicely, it should be fine. Some have reported the buttonholers works better on the old straight stitchers, but the later version are very similar. You might prefer to use your 15, especially for layers of heavier fabric.
Last edited by Mickey2; 06-14-2019 at 05:07 PM.