My Honda3011H usually does not start. A small engine mechanic said it's the seat switch so he bypassed that. Still the same problem. Only starts ones in about 10 tries. When you turn the key to start, there is no click or any noise. Once in a while, its starts fine and if I shut it down it will start again. When I leave it unused for a week or so it won't start again. Now somebody tells me it may be the starter solonoid. Where is the starter solonoid located, where can I buy a new one and how do I replace it. Thanks in advance for any help, Stephan

You could wire a 12 volt bulb across solenoid terminals to see if it is getting voltage while cranking, and not ignition switch.
Follow Battery Cable, Starter Cable, or look where you hear the click for the solenoid Location. If it clicks and has good voltage, it may be the Starter.

Thank you for this answer, the problem is that if it does not start, I never hear any click or any sound

Yes, and if you see the light lit up and it doesn't click, the solenoid is bad.
If it doesn't light up when cranking, the ground from the safetys, or the hot from ignition is not making it to the solenoid.
Need to test which is not making it to the solenoid, the hot or ground.

Thank you very much again. I will check this out
I do have one more question though. I the solonoid the small metal box that is attatched to the starter? Stephan

Hi, The solenoid is mounted on the side of the starter itself. The starter will be cylindrical and on the side of the engine and is about 3 x 5-6" and outrageous in price. The solenid is a shift-type and is about 1 1/2" x 3" and expensive in its own right.
This not the common cause of this problem on the machine named. There is a control module mounted to a vertical frame member near the engine and covered by a plastic cover. Wires can be seen visibly going to it. Remove the cover and carefully unplug the plugs and plug them back to ascertain whether you are the victim of galvanic corrosion. Often washing the machine will get water here. Washing is highly discouraged. This little circuit board is also pricey, as is anything with the Honda name.
Peace,
Clarke

Thanks Clarke, this will help a lot. Stephan