Upholstering Instructions at Better Homes and Gardens. In a nutshell: Strip the chair of its original fabric and use the pieces as pattern. Then pin the pieces wrong sides out onto the chair. Remove pinned cover and sew it together, with welting reinforcing the seams. Put sewn cover back on the chair. It should fit like a glove!
Once a month, I add a cup of Distilled White Vinegar 1 Cup of Baking Soda (adding both neutralizes the pH but the bubbling action gently scrubs any debris you can’t get to inside the drum) directly into the drum and use HOT water for washing. Then, I add about ½ cup of vinegar into the fabric softener compartment and ½ cup of baking soda into the detergent compartment.