Sorry, still not buying it. The ‘party-switiching fraud’ sure seems like an urban myth to me, and I’ve seen no evidence to show it impacting an election other than folks saying it does. If you have data supporting this, please share it.
As for "Proof"; it's similar to the typical "there's no evidence" meaning it's been shredded, hidden, destroyed, etc. when any investigation of corruption is forth-coming. It's not rocket science.