Hello fran,
No you can't repair it because it will run erratically, you can get replacement foot controls only, normally YDK model, you don't need to have a replacement Singer control in fact the new control will be far superior instead of the button, any good sewing machine shop will supply a new control or you can get them on line, www.sewingonline.co.uk/instructions if you are in the UK or www.tandtrepair.com if you are in the US, ver easy to fit.
drivewithken@blueyonder.co.uk
July 2008