[Darkness]

Hi, and welcome on board.

To improve starting it is strongly recommended that you look closely at the condition of the power cable to the starter motor and the cleanliness of the connectors, especially the connection to the motor itself. The size of the cable itself was only marginally adequate when new, and the passage of time hasn’t improved them. Voltage drop from tired cables tends to mean you either get spin or spark, which doesn’t help starting at all. Oversize copper cables are available as an upgrade from standard: Exactstart being one such.
The rubber boot on the starter motor connection can trap water leading to corrosion at the joint (And another voltage drop). Take great care if undoing the nut to release the cable though, as the post it’s fitted to can turn in the starter body. Usual consequence of that is it rips the internal leads out of the brushes! Better to split/cut through the nut if corroded.