If you don't find the cover you could make your own, I bought some similar sheets on Amazon https://www.amazon.com/Outus-Moldab...=pebbled+abs+sheet&qid=1606075532&s=hi&sr=1-7 The 838 has to recessed bottom clips and two spring clips on the top that lock it into place. The bottom would be easy, use ABS cement, it's similar to PVC pipe cement and cut some small squares and glue on the back panel. The spring clips are much harder. ABS will get flexible around 130 degrees, you may be able to use a heat gun and get it to bend into the position you want. You can use woodworking tools for cutting plastic or you may be able to score and "crack" the parts, look on YouTube, I'm sure there's a few different ways. One of the oldest threads on the forum was from a guy that cut off the plastic spring clips from a sacrificial battery cover and he cemented it onto his new cover but that thread is long gone.
Hi thanks for the info but to be honest I ain't that clued up on stuff like that so wouldn't be able to do it