My 90 is fitted with a Discovery steering drop arm (for easy ball joint replacements). The retaining nut has a nasty habit of coming undone (by 1/8th of a turn or so - but it's enough to make the steering feel like i'm stirring custard). Until pretty recently, i would just nip it up every year or so, now it's coming undone every couple of days and it's really bothering me. I think I'm not bending the tab washer over far enough due to the fact that the steering guard makes access a tad more difficult. Should I apply a drop or 2 of thread lock?