Here is a link to a simple, effective and cheap repair (with pictures)

http://au.geocities.com/ozbrick850/door-stay_fix.html

I did this myself on my own two front doors and once to a friend's car. I've done it alone twice but a helper is useful when guiding the door back onto the pins. Takes about 30-45 minutes and costs next to nothing. My oldest fix is two years and still works fine.
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96 850T, Bilstein HD, IPD swaybars

Here is a repair procedure I used successfully several times. I think it is easier than trying to put a nut on a bolt inside the door post.
Good Luck

Door Strap Fix

Tools needed: Torx socket E8, Torx bits T10 & T40, Drill bit 13/64, Tap ¼ -20

Door Removal;
1 Disconnect the battery negative lead. (Optional)
2 Open the door and support it with a jack or axle stand, using rags to protect the paintwork.
3 Disconnect the front door electrical wiring by turning the connector anti-clockwise and pulling it out of the socket on the pillar. (Torx bit T10)
4 Release the door check strap by undoing the bolt securing it to the pillar bracket. (Torx bit T40)
5 Undo the grub screw that locks the hinge pin to the hinge bracket on the pillar. (Torx socket E8)
6 With the help of an assistant, lift the door upwards to disengage the hinge pins, and then remove the door.
7 Grab the broken strap attachment bracket with vice grips to hold it in place while drilling and tapping.
8 Use a prick punch to mark the center of the broken spot welds. Drill 13/64 holes through each spot weld.
9 Tap each hole with a 1/4-20 tap.
10 Insert 1/4-20 X 3/4 bolt with a (thick) washer and lock washer in each hole. (I used self-threading type because that is what I had in my assorted bold tray. They also tend to self-lock)
11 Tighten each bolt snuggly.
12 Install door. (Assistant recommended for alignment of hinge pins during installation)
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Tom 69-1800S, 72-1800ES, 96-850T,2000-S70 GLT-SE

That site is temporarily down. It is
http://au.geocities.com/ozbrick850/
Lots of useful stuff here

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)

Use the search feature and you will probably be able to come up with the website of the guy that shows how to drill it and use nuts and bolts to put them back together. I had one in the shop just the other day that had failed after it had been welded back together once. I simply used larger hardware, 8mm instead of the recommended 6mm and it worked awesome. I have repaired probably half a dozen or so of the door stop anchor points on the 850/S70 line using the nut and bolt method and it has worked out great for me. You still need to pull the door but you don't have to dick around with a welder and the repair is pretty darn clean looking when done. Check it out, I think you will like what you see.

Mark