Electrical Problem

[Chevyguy111786]

I had a problem with my ignition a while back and the shop i took it to said it was a faulty wire and replaced it. Works great. but now, when i put the truck in park...if i go "past" park on the column, the starter engages and won't stop till i put it in reverse...and when in park my reverse lights stay on.
I'm thinkin some wire is shorting out in the column, but i haven't taken a column apart before. how big of a job is this. i like to think i'm pretty good with wiring and pretty mechanically inclined, but like to know what i'm getting into before i do it. what should i look for? any other ideas?