Jeff, make sure you clean those bolt heads very well before you even think
of inserting the allen in there. One at a time (what I do) is squirt
penetrant on all the allens a good bit before I actually tackle them,  pick
each allen head clean as possible, then squirt again to flush the void.
Insert allen with extension (no ratchet yet) and tap it pretty good several
times. This gets the allen in there and also jars the threads. I then get
with the business, but carefully, so as not to strip the allen head. When
installing your squeaky (and greasy) CVs, make sure you do not re-use allen
bolts. Use new, triple-square bolts. The usual vendors stock these.
Good Luck....
Miguel

Remember when teachers, public employees, Planned Parenthood, NPR and PBS
crashed the stock market, wiped out half of our 401Ks, took trillions in
TARP money, spilled oil in the Gulf of Mexico, gave themselves billions in
bonuses, and paid no taxes? Yeah, me neither.