Expert: Martin Meyer - 8/18/2007

Question
I have a Seth Thomas carriage clock with movement A403-001 (Hermle 350-060).  It will not run.  The spring above the balance (the balance spring?) appears very stretched and loose.  Could this be the problem?  The escapement wheel turns fine when I spin the balance wheel.  The clock is fully wound.  The chimes also work beautifully.  If this is the problem, is this normally an expensive fix?  Thanks!

Answer
Hi Kim,
    The 350-060 movement has had two versions of the balance platform assembly. The older version suspends the balance wheel by a coil spring. This spring is about an inch long and is a loose CYLINDRICAL coil of very thin metal, with a u-shaped bend half way down which reverses the direction of the coiling. This spring is very delicate and, if touched, will seem pretty limp. This is all normal.
    The newer version has a flat balance spring similar to the hairspring on a watch. This spring, unlike the earlier type, is a FLAT coil directly above the balance wheel. Rather than coiling downwards like the older version, this spring coils outwards like a disk or saucer, and should be completely flat, never "coned".
    If your clock's balance spring looks like either of these descriptions, it is correct, and the problem lies elsewhere. Your clock may need oiling (should be done by a professional clock repairer) or it may just be worn out. The average life span of these movements is about 15 years (although this varies greatly depending on the individual clock). After that, the bearings wear out and the movement needs to be replaced. This is the only long-term fully reliable repair (as opposed to just overhauling the original movement). It is a fairly expensive repair, but prices on clock repairs vary regionally, so I can't give you an actual dollar amount.
    Thanks for your question.   Martin