I'm glad you found your problem. I pulled the control arm today, and the wiring was just fine. While I had it apart, I did notice on the trim lever (the trim switch is actually 2 parts...the lever that reads "trim" that we press up and down, and the electrical rocker switch proper, in which the trim lever presses the up or down on the rocker switch) that there were some rub marks on the trim lever. I slightly ground it down, and applied a light grease to the edges and pins on the trim lever. It works smoothly now, but I don't think this will solve my problem. I did replace the 10A fuse with a 15A temporarily and it worked fine, but I don't like using the higher amp fuse, so I'm going back to the 10A and try it again.
I found this page, and I think this is the trim pump I have-
http://www.volvopentastore.com/SX_M_MACLT_MDA_MDB_MHP_MLT_Power_Trim_PUMP/dm/cart_id.581787393--session_id.035611219--store_id.366--view_id.312861and it shows 2 filters (#6), so I may try to clean/replace those. This'll be a winter project as I don't want to have the boat down while there's still some hot days left (101 at the lake today).
Rick