Any appliance parts store that’s worth its salt will have the parts you need. The glowplugs can be hard to get to. Something to keep in mind… Never touch the part of the glowplug that gets hot. The oils from our skin will create hot spots and shorten the life of the glowplug. Going slightly off topic here, something to consider. Your clothes dryer. I would suggest taking the vent off and cleaning the whole thing out (vent pipes and the dryer itself). Doing this will help lengthen the life of the glowplug, and may prevent a fire. This is even more critical if it still uses a standing pilot.
I should add, if you use flex to vent the dryer, use aluminum or hard pipe. The vinyl stuff will cause all kinds of problems.
To get this thing back on topic, if you decide to make repairs yourself, more power to you.