Small Engines (Lawn Mowers, etc.): JD 318 starting problems, john deere 318, battery tray

Question
Have a John Deere 318 that won't start.  I believe it is a 1987 model with 869 hours.  Bought it used and ran fine then.  Stored in my dads garage while my house was being built.  Once we went to move it to my house it wouldn't start.  Had to jump start it and from there on It always had to be jumped.  Replaced battery this weekend.  Once I had the terminals connected I turned the key and it sparked at the positive terminal and never turned over.  No clicks or anything.  If I turn the key on and leave it after 10 seconds or so a strange humming noise starts coming from the battery area near the starting switch.  There is a black box in this area that has some wires coming out of it also.  Removed some side covers, battery tray, etc. looking for any wires being pinched or bare.  Found nothing.  Thats as far as I have gotten so far.  Used it once last year since I purchased it.  

Answer
 Hello Jim:

 Sparks at the Positive Terminal? Was this the Battery Terminal. If Yes, then Retighten the Connection. Make Sure the Cables are on the Battery Correctly. **DONT GO BY WIRE COLOR** The Black Box is the Interloc Relay. This is a Part of the Safety Switch Circuit. Hope this Helps. I am here if you Require more Asistance. Thanks.

 Good Luck

 Respectfully

 John