This is a very common question we get about hot glue guns. Repairing hot glue guns can offer excellent cost savings but typically not on tools under $300. Most manufacturers don't offer spare parts on their entry and mid level glue guns making them more difficult or even impossible to repair. Guns the the TEC Bond 3400, 6100, 6300 and the 3M Polygun EC and PG II are good examples of higher end glue guns that can be much less expensive to repair than replace. Gluegun.com also offers a repair service for almost every industrial glue gun we sell.
Kind of a loaded question but a common one. If you are very familiar with your glue gun and are a hands-on person, many glue gun repairs can be done in-house. There usually aren't a lot of components to a glue gun (unless you get into the larger spray or pneumatic units) but if a spare part and repair is needed, be sure you are comfortable taking the gun apart and putting it back together. Also, many times a repair isn't done by a Certified Repair Technician, the manufacturer will not warranty the spare part or gun, so keep that in mind before taking your unit apart.
No, not all hot glue gun manufacturers provide spare parts. Gluegun.com has an extensive line of hot glue guns and access to all of the spare parts available for our lines. However, many times manufacturers won't provide spare parts because it isn't cost effective or the demand simply isn't high enough.
The most common spare part we see replaced on hot glue guns is the nozzle. Often times, if the nozzle goes bad (thread gets worn, O-ring breaks, etc) you will see the glue gun leak or drip excessively. The good news is this is usually a pretty cost effective repair and most of the time these parts are available. Check out our article on How to Replace a Hot Glue Gun Nozzle for more information.