Call SoCal. I have had my '37 on the road since the mid '70's and never had a shackle problem. When installing them I use a graphite like Never Seize and I do preventative maintenence now and then. What front axle and length spring do you have? Although I don't see how anything to do with that could make the shackles freeze up. Are the spring and the kingpin inclination at the same angle so the shackles don't bind? Maybe ajustable spring perches would help if there's a problem with the angles.