It happened to me twice after fixing a broken capacitor that the mirror still didn't come down. Then I dashed them quite strong in my palm, et voila, they worked and din' fail anymore afaik. Good to know that there is a better way :-)
A couple of years ago I bought some defective X-300, 300s, or 370 Minoltas at the bay or on flea markets for almost nothing and was able to repair almost all of them with these 2 tricks in maybe 10 minutes, having a stock of new capacitors at home. Cost: 20 cents