I bought the Wallytractor Universal and love it. It will solve the problem you're asking about and then some.
The good thing about the Wally Universal, it works on linear track, and pivot arms. Pivot arms it works with include 9" and 12" in both Baerwald and Löfgren formulas.
http://www.simplyblack.net/WVC/index_wally.html
The good thing about the Wally Universal, it works on linear track, and pivot arms. Pivot arms it works with include 9" and 12" in both Baerwald and Löfgren formulas.
http://www.simplyblack.net/WVC/index_wally.html