Glass cooktop keeps cracking in same area

Question

I have cracking on my 4th glass cooktop in 2 years. The last one is only 4 months old. Help find the answer to why I even tore off the entire top from the island and had everything absolute level.Authorized servige installed the top. Absolute level. 4 months and it cracked again in the same place. service man says the double ring element checked out o.k. but there is something wrong Help