First I'd test the motor and solenoid pack separately.
Test the motor alone with a booster pack or a battery
with jump leads - touch leads on the motor terminals direct, no solenoids or switches.
Multimeter on continuity will determine field & armature terminals if it's a 3 or 4 terminal motor.
If it doesn't run clean the commutator back to bright metal when replacing brushes. Maybe you did that but you didn't say.
Also clean out the segment separators & re-cut them if they need it, ie. if they're sticking up above the commutator segments.
If new brushes have square ends I'll often trim them to fit the commutator better at first starting.
If you're unsure of your wiring
there are some diagrams in Lofrans online manuals
for connecting their vertical winches with 2, 3 or 4 terminal motors.
If motor runs OK wired direct then check solenoid wiring
& remote - you don't say if it's a wired or wireless remote?
What "solenoid between the brushes?"
You said you replaced the solenoid - standard Lofrans is a reversing solenoid - that's two solenoids in a plastic housing.