how to safely stall a DC motor

I'm in the process of completely retrofitting an Emco Turn 120 cnc
lathe. It's got an 8 position tool turret on a ratchet mechanism,
driven by a small DC gearmotor (24VDC ~15watts) through a worm gear.

In operation, the motor spins the turret forward until the proper
tool location is found (a small sensor board senses each position)
then the motor reverses and then stalls out holding the ratchet pawl
into the ratchet teeth. This in conjuction with the gearmotor and
worm drive help to hold the turret in postion during machining. Far
from ideal I know, but at this point I want to make the existing
setup work rather than redesigning/rebuilding the whole tool turret.

I've found somebody that has my same machine, but in working
order, and has verified that the motor sees 24VDC while in forward
operation, and 2VDC while in reverse/stall. From the manual they
show a basic H-bridge circuit that drives the motor but virtually no
details. At this point we are guessing that the motor is driven with
PWM and the 2V we see is about a %10 duty cycle average voltage etc...

So, how do I go about controlling the direction and current of
this 24V 15watt motor, such that it will see 24V and full current
during turret indexing, but then be able to reverse and remain
stalled for LONG periods of time without burning itself out?

Would it be feasible to simply control the motor with a DPDT relay
that supplies 24VDC for forward operation, and then supply 5VDC and a
resistor of some value for reverse/stall operation?

I'm not an electronics guru, so designing and building a circuit
would be very time consuming and difficult for me. I'll be
controlling everything with Mach 2. Thanks for any advice.