Hey not sure if its the same problem- but my speedo used to stick when I parked the car in the hot, then when I drove the needle would stick and not read accurately, as well as not properly dropping back to 0.
I took the cover off the dash (it was a while ago, but i think it was about 5 screws) and the non-needle side (the bump which sits opposite the needle part of the pivot) was catching on the backing which has the speed numbers printed on it. (probably bending it out ie towards the driver, when it got hot- but it may just be bent in your case on the lower speed side of the speedo)
on this print on there are two Philips head bolts right near the odometer. wind these bolts out a little and push in the corner of the print on into the hole where the odometer sits to bend it out of the way (into the odo hole) of the needle which it was catching on. then wind the small philips head screws back in so it stays bent out of the way of the needle. then put the dash housing back in with the (4-5 screws)
Not sure that this is explained very well- but it saved me from fiddling with the speedo cable (when that wasn't the problem) and saved me from buying a new speedo cluster (which was going to be my next option).
I did this a couple of summers ago now and I have had no problems since. At the time I had no mechanical knowledge- so I suggest checking this first as its a really easy thing to check to see if the backing which the speed is printed on is simply bent and catching on the needle before looking for other causes (even though catching speedo cables do seem to happen regularly)
Hope this helps
