Your 741 might still be under warranty if you bought it new. Secondly, maybe it didn't get "fried" but it got water in it. I had a Geosatpro unit once that I took apart, dried and cleaned out and it worked fine after that. That works maybe a third of the time though.
I just bought oned of those orthomodes from linuxman. Save a bunch of money buying it used. Very expensive new.
Looks like you have a BUD (big "ugly" dish) and LUD (little uglier dish) I used a BSC 621 for awhile, but you have to get those right on the money in order to get both bands. I was using a Geosatpro C2 (no servo - voltage controlled) for just C-band. If you have DirecTV, getting Ku off of your big dish might be redundant.
The orthomode is supposed to be an advanced solution, but I guess my luck is holding as I got it working essentially the first time.