Ref MasterMix MC130 Cement Mixer?

The On/Off switch is faulty---I have to hold the on switch down to keep mixer running. 1. Do I need to buy a new switch and if yes how do I remove the housing to get at the switch. 2. If a new switch is to be purchased are there any updates of the switch to take into consideration and are they interchangeable?. 3.How do I find the Mixer's Model numer