Super glue or epoxy that sucker back on!
But seriously, according to the link above, can't buy just the switch, have to buy the entire electronics assy which includes the motor stater for $190. If that's the case that's stupid!
IIRC MW has flate rate costs for each tool. Can login or create an account online, enter the tool info & it will tell you how much the flate rate repair cost is. Or if you have a local repair center can go there too.
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I suspect for that impact the flate rate cost will be close to what that electronics assy costs.
Also keep in mind, MW will cover the shipping to them so it's free to send in. They'll give you a quote for repair but IIRC if you choose not to have it repaired & want it back, they'll charge you for return shipping AND they'll send it back to you in pieces (they won't reassemble it if they disassemble it for inspection). Some **** about they don't want to be liable for sending back a tool in insufficient operable condition.
If it were me & glue don't work, I'd open it & look for a p/n on the switch. But then again if you do find the switch it might not come with the trigger? If no other option, hate to say but at those prices for repair I would buy a new one after being pissed for a couple of weeks.