A quick look at the illustrated parts breakdown for the LX188 (PC2317) on the JDParts website suggests to me:
1. remove the steering wheel.
2. disconnect the drag link.
3. remove the four bolts and nuts on the lower bracket.
4. drop the steering gear out of the tractor.
5. remove the cotters holding the splined parts together.
6. Pull the splined parts apart.
7. Inspect, repair, replace worn parts as needed.
8. Lube all the rubbing parts.
Don't know what's in the maintenance manual on this, as I don't have one (or an LX188). But I'll bet it's close to the above, assuming that there is a procedure there.
In short, look the parts breakdown over, look the job over, and have at it. Splines may be rust-frozen; if so, soak them in a good penetrating oil like 1/2 each acetone and trans fluid, and use a press if needed.