It's pretty common for small bits of glass to get into the main wash motor and cause trouble. Only way to find that out is the take it all apart and look for debris. I recently took apart a non-washing Thermador dishwasher and found the was impeller completely split in two. I've had some bad motors on LG dishwashers due to bad bearings. Yours is part number 4681ED1004B and should cost a little over $100.