This two button Aux switch replacement footswitch will allow you operate your Roland JC 40 Jazz Chorus Amp. 

It will toggle the Chorus/Vib, Reverb, or Distortion of the amp. (must hook up to two of of the three) For example, Chorus/vib and Reverb, or Chorus/Vib and Distortion, etc. 

* You will need a TRS Y cable. Please find it here: https://www.sweetwater.com/store/detail/IPBQ2Q20--pro-co-20-foot-ipbq2q-20-1-4-inch-trs-to-2-1-4-inch-ts-insert-cable