As albmn10 posted, roll slowly foward/reverse with the wheel turned most of the way to the stop and it may be easier to get in. It almost always will go in when lifted.
If you want it to be a lot better, open the platform and follow the linkage to where the 4WD levers meet other parts of the linkage, on the CK20 it's connected with the range selector, not sure on the 45, but there are round parts of the linkage that you should pull off and fill with a good grease. This is a good location to have a zerk added.
You may need some help with the platform of the DK45 as it's much larger than the CK20, but it's not a hard process to do.
You might even be able to get a can of the white lithium grease with a straw on it to blow some grease into those linkages, but I'm not sure you'll be able to access them without removing the platform.
John
EDIT: I would also spray that delayed viscosity grease on any elbows of the linkage just to make them all slide more easily. J