When is it time to step back from the project that you are determined to fix yourself? Well, if you are like me, that time is never. I can build or fix anything around the house or anything mechanical. At least I have convinced myself that I can. In reality, I may not like it, but I do know when to step back and let a professional do the job.
The time to step back is when special handling or specialty tools are needed to do a specific job. Electricity is a great example. Every year people are hurt or worse because they try to do what appears to be a simple repair. Changing an outlet or replacing a light fixture is relatively straightforward but if you have never done it before, it can be dangerous.
So am I saying never do it yourself? Absolutely not. As long as you do it safely, I say go for it. How else will you learn how to do something unless you try to do it? Worst case scenario is that you still have to call someone to fix it. If you do call someone, ask what you did wrong. Most technicians will let you know. And if you do not want anyone to know that you tried to fix it, blame it on your old uncle Bill.
Lawn and garden equipment is no different. Always think safety! Before working on anything, remove the spark plug wire (just remember to hook it up when you are done). You can normally perform routine maintenance on equipment without voiding the warranty (just read the warranty statement carefully to ensure this); you can change your oil, air filter, spark plug, with no problems. Just make sure to use original parts from a local service center. And if you do not know something, ask. Most shops and even the manufacturers have people that will answer basic questions. Just be careful not to exceed your skill level.
If your chainsaw or trimmer or even lawnmower will not start, do not rip off the carburetor and attempt to rebuild it. If you have never done this before proceed with caution. Some carburetors are very complex and a simple nick inside the carburetor can damage it beyond repair. If the repair is beyond your comfort level, bring it into a service shop. They will be happy to repair it for you.
However, if it is a fuel related issue causing your machine not run, remember that Mechanic In A Bottle will fix non-running and poor running engines. Once running, always use Ethanol Shield and the Gasoline Tank Snake to keep the gasoline fresh and ready to use when you need it.