two-words: di-electric grease (on all the connections)
Mebby not in this application. Dielectric grease has been assigned some magical properties by users, but I'm not so sure it lives up to the reputation. The main properties of dielectric grease are that it is a wicked good electrical
insulator (as in opposite of conductor) and by virtue of its own bulk filling nooks and crannies prevents water from entering those points. When you pack any socket or connector with dielectric grease you are packing it with an electrical insulating material. In the case of bulbs that twist into a socket like the common 1157 tail light bulb, it prevents the bulb from freezing in the socket and allows bulb removal without twisting the glass envelope off the metal base.
If the GPS electrical connector is intermittent the four most common reasons are:
* The power cable has a poor connection at the power & ground source.
* The cable has internal broken wires.
* The power cable has eight contacts, the contacts are supposed to be mounted in the connector such that they have some springiness to them. One or more may be worn/bent/tired. Look at the connector end on and see if the contacts are straight and of equal height.
* The contacts on the back of the GPS may be dirty. Put a few drops of isopropyl alcohol (rubbing alcohol) on a paper towel and lightly wipe the contacts to remove surface grime. Now very, very lightly rub a lead pencil eraser over the contacts. There is just enough abrasiveness of the good old yellow #2 eraser to break oxidation without taking all the gold off the contacts. This is a favorite of many electronic techs.
The suggestion to try another power cable or different mount was a good one.
Edit: I also have a 2730 and among its quirks, "cutting out" on bumps is not one of them.