Hairspring for Ingram 8 day Broadcast alarm clock

by Tom
(Silverdale, WA)

I have an Ingram 8 day Broadcast alarm clock in need of a hairspring. The original was the victim of a botched repair attempt and only part of it was in the clock when first acquired. I attempted to use a hairspring from a collection of standard springs, but the clock looses approximately 1-1/2 hrs/day. I have found a source for hairsprings (www.britishprecisionsprings.co.uk/index.html), but have no idea of the torque needed.

I have an assortment of hairsprings, but all have collet bores too large for my balance (1.0 mm). The only collet size that will fit will cause the clock to loose time (as mentioned above). Any advice will be appreciated.