Headlight aim no workie

I am new to the forum and new to Volvo. We just bought my wife an 01 S60 with 42K miles on it, but I have some "used car issues" to work thru. One of them is the right side headlight aim adjustment doesn't work. It appears that the adjustment is to the internal focus piece (or whatever you call it) and I guess mine has jumped the track? Can I get it threaded back in to the adjuster myself, or do I have to replace the headlight assembly? TIA for your help.