If they are too tight, it may be that the contact part of the connector was somehow bent, and may not be putting even pressure on both sides of the connector. be sure to always take a quick look into the connector housing to insure that both tips sit in the housing the same, and that there is no cracking or flexing of the flat piece of plastic (down inside the housing) that puts the pressure on the spring. be sure to check all 3 halves (truck, charger and battery) and be sure to make sure that the charger half does not lay on the floor where it can get run over, running over the charger half is what sometimes puts a bend in the metal parts that creates a bad connection, which in turn creates heat while charging that can eventually cause a failure of the matching connectors (battery then truck), although the battery connection is not supposed to be something a child could disconnect, (and so a small women may have difficulty. also).
The type of connectors you have now, (that we are talking about so far) we call "SB" style connectors. as work arounds, there are other types of connectors available that may work better for you, but may be more expensive per connector. but may also last much longer. You may want to consider the EC style connector, as it has a cam lock type lever to insure connection, that takes less effort to disconnect. there is also a YC type of connector, where the grab handle is part of the housing.

no grease, they are made to work together without any lubrication, if you lube then it will cause problems later on. dirt buildup etc.
if they are that tight like bb said, replace the connector housings. they should be fairly easy to pull apart and slide together.

Have you tried a small amount of dielectric grease like NOOXID on the contact tips?

I've had to replace the housings to loosen up the connection. There are no adjustments. Remove the electrodes & see how tight the connections are without them. If still extremely tight- replace housings.

We actually do have the handles bolted on the connectors. And use the wiggle technique. Is there any adjustment that can be made?

a tight connection is good but wiggling the connector helps, or you could contact your local industrial battery company and get a handle to help make it easier. yes they make a handle that bolts onto the battery end connector. It gives you something to grab onto instead of the cables or the connector body.

I'm suprised the local tech didnt suggest this, i would have