I have a Commodore Speedwriter that I hesitated to buy when I first tried it out in the shop where I bought it... it tended to skip spaces at random and frequently (and most frequently after an 'a' stroke). But I liked the look and feel of it so I negotiated a lower price and brought it home. I gave it a mild cleaning with denatured alcohol and then ran a few sheets of typing through it. The space skipping gradually disappeared til I was able to count just 'one' on a full sheet. When I brought it out a couple of weeks later and typed a few paragraphs I found the 'a' skip had reappeared. I persevered into a couple of full pages and found I was back to a about a single 'skip' per page... so I think -- that just like cars -- typewriters like to be used, and perform best when they are used regularly and often. Most typewriters can't hope for such treatment these days.