Depending on the glue used in the construction, Resorcinol was commonly used in the 60's and 70's but its life could be somewhat suspect after 40+ years. I recently considered buying a Piel Emeraude (often called an Emerald, but incorrectly named), but it was also built in the 70's and a very experienced plane builder suggested that glue was probably getting to the end of its useful life. The one I flew performed very nicely. I hope it can be repaired and flying again