I want to buy this pop up camper but the wiffel tree is broke i was wondering how hard it is to fix it and how

It is not difficult however, it may not be broken. First, verify all the pins in the crank linkage are not sheared and thus not turning the wiffle screw. There is on not visible from the outside. Under the camper is a rectangular tube usually mounted between the 2nd and 3rd crossmember. It is just a cover. Remove the cover and near the front is the probable culprit. Just turn the crank and look to see if the wiffle tree screw is turning.

If the handle won't turn or is very hard to turn, the wiffle tree is likely bad. The four cables are attached with welded closed eye-bolts. Just back of the nuts and remove them keeping track of where they go and how much exposed thread is showing. This is the adjustment for the cables to ensure even lifting. On the front the 2nd crossmember is a thrust bearing under a small rectangular cover. Remove the cover, seperate the crank linkage rods and remove the bearing and it's spacer as a set. Pull the wiffle tree screw with the bar the eye-bolts were attached to, forward. It may need some persuasian but it is just a slip fit in the rear and will come forward to remove it. Install new one in reverse order.