Small Engines (Lawn Mowers, etc.): Dixon ztr7052 starting issues, resistance in a wire, battery cables

Question
Eric .. The Dixon will not engage starter and roll engine with key .The piggyback bendix will throw out the gear into flywheel but will not rotate engine.It seems that thru testing ive found that starter relay was bad so replaced,the starter was alled gummed up,took it apart and cleaned I know that it will work when tested on battery off machine but it wont on it.Even with 10.8 volts at the exciter wire the bendix will fly out into the gear but the only way i can get the starter to engage is to run a jump wire from battery to the tab on the starter.Im not sure if I have a safty switch issue going on but I do know that the new relay will not engage the starter if I try using a remote start switch.I dont have a wiring diagram and i know im overlooking something simple but i dont know what that is.ITs like the system is lacking a ground somewhere but im not sure where it could be.Ive searched this thing for a week trying to get to the bottom of it but the way it acts will not let me pin it down.I also tried a new key switch thinking that was where the voltage drop was but it didnt help.I need another set of eyes and ears on this thing.Thankyou for your help

Answer
I have had a similar problem with a Snapper zero turn years ago.  Try running another, larger wire in parallel with the solenoid exciter wire.

You mentioned voltage drop.  Do you know how to check voltage drop across the battery cables?  This is an important test that can save hours and money...learned from experience.  Had an old Ford truck as well with the same problem...turned out to be a bad positive cable and was easy to find by measuring the voltage drop across the cable.  The voltage drop is similar to squeezing a garden hose connected to a sprinker.  The tighter you squeeze the less the sprinkler squirts water...this is simialer to resistance in a wire/cable.  Although current is the electric circuit workhorse voltage is important too.

You can Google how to measure voltage drop.  Lots of articles and You Tube videos.

Let me know what the voltage drop is across the positive and negative cables as well as what happens when you run another solenoid exciter wire next to the existing wire.

Eric