So my son is getting some old Lionel Scout locomotives from gramps, and these locos have not been ran in decades. What steps would you recommend that I do to these locos before running them?
Inspect armature and brushes for damage or need to clean . Make certain the motor turns freely. Clean wheels and pickups if necessary. Be certain there are no carpet fibers, pet hairs etc, in the gears and wound around axles, etc. Lubricate lightly. Also, look at the 110vac power cord for any transformer, for any cracks, etc.
Lubricate. Depends on version of Scout as to how much success you will have. If it is a clamshell, be very careful. Found by seeing two halves of motor case, split down the middle, breaks up like Bakelite but probably just plastic gone bad. Rollers are cut off pieces of tubing retained in the bottom. E-unit lockout lever is a fibre lever that moves for and aft, not athwartship. Axles, gear idlers, especially ends of armature shaft. Car and tender axles. Sewing Machine oil is what I have used for decades and decades. Before I had empty LaBelle oilers to refill, I used curved tip hypos you get from your dentist for irrigating extractions.
Later Scouts had open frame chassis with sometimes even a 3-position e-unit. Let me know if you have issues with a clamshell. I'll walk you through it.