Transmission problems

Help needed - i don't want to get ripped-off!

My '95 Cherokee Sport has suddenly decided that it doesn't want to change up and down the box. On starting the car and selecting "D" it will engage 1st and cycle smoothly through to 3rd and OD, however it won't re-select 1st or kick-down after this. I can manually select 1-2, but only get 1st. Hard acceleration from 1st and manually selecting 3rd will briefly see 2nd.
Is this a problem that anyone else has come across and if so what is the likley problem. I would like to have some idea before someone takes me for a ride.

Thanks

Check the fuse that says "trans". this blown fuse did somthing like that to mine.

Check the TCU fuse, below the dash, just back of the glove box. Its an in-line fuse.

OK, i'll check the fuses. However last night on a longer than usual drive to the airport it started to act normal again, all changes up and down the box we sweet. My guess is that it's not mechanical rather than electrical, but then I have absolutely no idea about auto boxes!
Any further suggestions would be appreciated.

Loose connection in the power feed to the TCU?