I am seeking help to identify some screws that are missing from my heat pump condenser unit. Yesterday while mowing around my Trane Weathertron XE1000 heat pump I noticed that several screws were missing on the side panel and around the top panel that houses the fan motor. Apparently the HVAC tech that serviced my unit last month did not replace all of the screws when he was done. I removed one of the screws and after doing some research on-line I found out this much about the - They are unslotted, indented, 5/16" hex head washer type, the threads are 1/2 inch in length and appear to be zinc or galvanized. There is a sharp point on the end. I went to my local big box stores but they did not have an exact duplicate. I can't tell if the size is #8 or #10 or some other size. I went to the local Grainger and Johnstone Supply and I was told they did not have an exact match either. Can anyone help me identify the exact name of this type of screw and the specifications and possibly give me a source on where to purchase these * Thanks!