It has been my experience that there are two main reasons for linear air compressors to fail prematurely. Besides high back pressure (clogged air diffusers) which is the main reason for failure the second most common reason is FIRE ANTS! I hate them, no really hate them. Preventative ant poison placed around the air compressor housing is very effective in keeping them at bay. It is tough to remember to do on a regular basis but if you are treating the yard then by default the air compressor benefits. Here is one picture (of many) showing the devastation that these little guys cause.
The result of the ant infestation is that they cause a short inside the housing of the air compressor. If you are fortunate it can be rebuilt but if not then replacement is the only choice. Sometimes you can buy the internal parts but it usually becomes more cost effective to replace it instead of buying the inside parts. Some folks actually put the ant poison inside the housing that covers the air compressor. Anything that you can do without harming the air compressor to prevent the ants will help to prolong the life of the air compressor.