What kind of issues do have with the CB? Is the CB currently in your Spyder the second or third one? If you still had/have problems with the replacement CB then it's likely something other than the CB radio unit itself. Dealers are not well versed in CB technology so you're better off to go to a CB radio shop, if there is one available to you. I sent my first CB to Radio Sound but they wouldn't touch it after they opened it up. I had had water inside. I don't recall if they charged for the diagnostic or not. They may repair yours, if in fact it is defective, for a flat fee.
Was the CB included in the deal when you bought the Spyder? If so it most likely is not one of the earliest ones which leaked water, i.e., 2010 to 2012 model years. If you bought it off eBay, or something of the sort, it may have been defective when you got it. There were 3 or 4 generations of CB units. You probably ought to check the part number on the CB to see which generation it is. I wouldn't put it past the dealer to install an older generation one.
Otherwise, a possible culprit is the headset cord. I went through a half dozen cords before I finally ended up getting a J&M headset that has been OK. The earlier ones were Air Ride and Edsets. The headset cord is prone to shorting out internally. Do you have the correct headset for the BRP CB? It needs to be one with a preamp built into the cord.
Also the antenna can be problematic. I ended up installing a No Ground Plane CB antenna from Firestik. The downside of it is it uses a 17 foot long cable that I managed to coil into a figure 8 under the seat. A round coil doesn't work. Make sure there isn't a bunch of thread lock on the antenna thread where it screws into the antenna block under the tupperware.