1979 MTD Rider Thought Battery dead, replaced but no power yet?

Bought an old MTD lawn tractor very low horsepower, one year ago. Ran fine but one day battery died (or so I thought). Charged it, but still no power so I replaced battery, charged new one (dry cell) but still no power. Volt readings are fine. Wiring is old (battery cables old but seemingly intact). I think wiring was messed with because battery wiring does not go directly to the ignition but has several splices, etc. My dad insists it is the Ignition Switch but I think it is a wire problem but have no diagram. Any help would be appreciated! Thanks, m PS along the wiring path is a bright red push button, plastic, that pushes into a red rectangular body, but pushing it does not make it click, it just pushes in and out. I am pretty sure it is not an inline fuse but have never seen one like it? any thoughts? I think we need to take the back cover (where the battery is) off to examine the wiring more thouroughly but Dad thinks it is too difficult. THanks, again. m