Hummingbird help!

I bought a used boat that came with a Hummingbird Pirahna MAX 10. The cradle that the unit sits on is broken and the transducer on the transom is hanging because the plastic holding it is broken.

My question is probably obvious: I am primarily trolling for crappie in the future with this boat. Is it worth spending the money on the new cradle and transducer or should I upgrade to an all new unit?

If the latter, can someone give me a good, middle of the road suggestion on a unit? Maybe a few suggestions based on spider rigging and pulling Bandits... I fish the reservoirs in MS if that would be helpful in suggesting a unit.

Thanks!

Hummingbird 565 I'm happy with mine cost bout $170 to $200 depending where you can find the best deal.