The idle control switch allows the generator to go into idle when there is no demand form the appliances connected. This saves gas and increases the life of the generator. Damage can occur for some appliances like a refrigerator/freezer because the voltage and frequency are not prepared for the load resulting in a low voltage bad startup that will damage the appliance. Suggest that you leave the idle control switch off while any motor/electronic devices are connected.
The throttle control is likely a choke function for starting. These generators are designed for only one running speed to produce the necessary 60 cycles per second and voltage.
The following link is to a Canadian web site that later in the detail report describes the concern of idle control. In addition it provides good insight to the operation and use of portable generators
you should be able to do it by ear,With a load on the unit you should be able to idle it to where it sounds like it is not running to fast and that it is not running enough to keep it from triping the reset.it should sound smooth. or idle it to around 2000 rpms or lower.
You need an multi meter, on the ohms scale. Short the two prongs on the cap out, removing any voltage on it. Put your meter to a mid range ohms scale. Touch the leads to the prongs on cap and watch your meter. It should start climbing in value and then go to 'OL' if it's digital. If it's an analog meter(with a needle) it will go all the way over to 'infinite. This means it's good. If it's bad, it will just read 'OL' or go right to 'zero' meaning it's either shorted or open.
A micro welding torch should be a smaller version of a full size welding torch - identical apart from size. It is most important a user thoroughly familiarises himself or herself with the correct usage and safety precautions because failure to observe the correct procedure can result in extreme danger. A flashback can have potentially serious consequences...
A person who is thoroughly conversant with the procedure and safety will know how to connect the hoses to the welding torch and to the cylinders - if it is a quality unit, it is an intuitive process due to the fuel gas fittings being left hand thread and the oxygen normal or right hand thread and the hoses are or should be different colours with blue being the norm for oxygen and red or orange for the fuel gas.
One final word - never, ever, under any circumstances use a lubricant on the threads of the oxygen bottle or associated fittings...
A great many older home mig welders were produced with a live torch, ie. the manufacturer had saved the cost of the contactor, the high current electromechanical relay that switches the welding current on or off in response to the torch trigger...
It was inevitable some manufacturers would replace the rectifiers and contactor with thyristors (SCRs) and obtain both functions from a single modification.
The trigger switch controls the wire motor and the contactor so if the wire motor is working ok it is unlikely the fault is there and if your welder has a contactor it could be stuck or a wiring fault has caused the coil to be permanently energised or if your welder uses the solid state version, either one or more of the thyristors have failed or a circuit fault has caused the supply to the gate to be permanent causing them to be permanently switched on.