A couple of points which I have come up against with Disco 2 door latches.
Yes, I have heard of the possibility of replacing the faulty solenoid/motor within the case with items from such places as Maplins. To do this, of course you either have to have the parts available prior to doing the job or you're able to get to the supplier in another vehicle or you refit the old lock or you leave the car unlocked until the parts arrive. I prefer to purchase a replacement latch before doing the job.
All five latches are generally similar to replace, the main differences will occur with the rear tailgate door and the driver's door. In the case of the four main doors, the window frame will have to be removed, or at least almost removed to allow enough room to manoeuvre the latch assembly out of the door. The driver’s door has the added fiddle of having to insert the small bar between the back end of the lock barrel and the latch to allow for operation by the key. Once you have the knack of disassembly of a door, a full strip down to replace a latch should take an hour or two. The latches are specific for each door.
On the subject of new latches, be prepared to find that you have a faulty one sometimes, so don't throw the old one away until you're certain that the new one is working correctly. I fitted a new latch to the rear nearside door and found that it was faulty, it worked correctly when locking and unlocking, it worked correctly when opening it from the inside but it felt like the door needed alignment because it needed a damned good tug to open it from outside. I replaced it with another unit and all was sweetness and light again.
I haven't had problems yet with the RF receiver in the roof, but from what I do know as a radio engineer is that moisture and corrosion are the number one and two enemies of the little RF unit. Sometimes the inside of the little box can get damp, even soaking wet and that ain't good, the other problem which can occur concerns the earthing nut on the outside of the RF unit. Corrosion there can cause the working range, usually in excess of 20 feet to reduce quite significantly and that can result in "The Disco Dance"; dementedly waving your arms about and standing on one leg while touching the key on your head and pressing the unlock button at the same time. If the RF unit has got wet, then once it's been dried out it should be closely inspected because such conditions can cause irreparable damage to the electronic components. Under such circumstances, a replacement unit must be purchased, cost about £30 or so. I believe the operational frequency band is 433 Mhz.
