My dryer will only run in two positions. I checked the fuses with my multimeter and all seemed good. I think I am having a problem with my timer. How do I know if it is the timer or something else?

Checking the timmer for proper operation requires a timmer chart and the proper electric test meter.This is difficult to do even for a trained professional. Usually they just replace the timmer if in there opinion they believe it is defective. Timmer charts are all different depending upon the model and usually the chart is in the factory repair manual if you can find one. You might check with sears parts to see if a manual is available.