Exterior Door Threshold issues

[bkt64]

I really looked where I could post this in a more appropriate location, but found nothing on exterior doors anywhere. Advise if there is another better place. However since I am here, I have a front door that has had issues for the past several years. Seems it has been leaking and wood and threshold have started to rot. I have made temporary repairs for the winter but need to do something more serious next Spring. I have tile to the threshold on the inside. I want to remove the old threshold and put in a new threshold. I found one identical at Lowe's but no one there could answer my questions. Is there a way to remove just the threshold and the rotten wood on the door jam and replace them? I have included picutres. The rotten wood is not included in this picture, but I have labeled where the rot has occured. It may just be easier to replace the door but hoping not.

[pushkins]

Someone has repaired that door before, evident by the cut in the jam.
Basically your going to have to cut out the rotten jam and replace it with a new section (jams are available at big box stores) the threshold is attached to the jams on either side staples are used from the underside of the threshold up into the jams. You can cut and wiggle the threshold out if the jams are in good condition but in your case you might as well cut the bottom of the jam and then the threshold will come out with it.
Maker sure when you install the new threshold that you run a good bead of silicon under it towards the exterior edge.