I have been an avid watch enthusiast for the last 10 years or so, and in that time I have tinkered with the odd watch or two. Having recently semi retired, I have helped out friends whenever I could by replacing batteries in their watches, repairing and replacing clasps etc, and I have somewhat become the go to guy in my village for minor repairs. One of my friends asked if I could look at his retirement watch, a gold Sekonda, where the stem had pulled out of the movement when he went to adjust the date.   I did warn him that this may be beyond my capabilities, thinking that the keyless works will need working on, but said I'd take a look at it, as it may just be as simple as replacing the stem while pressing on the release lever. I opened the watch, removed the movement and tried replacing the stem, but even though it clicks back home, it falls out when pulling to position 1, so obviously the keyless has failed. The movement in this watch is a Miyota 2115 and can be bought on Cousins UK for the pricely sum of £3.55, however Cousins list two variants marked (3H) and (6H), the latter being £3.65. I am uncertain as to what the designations refer to - is there a 6 hand version of this movement? or does this refer to the height of the handstack? I'm assuming the (3H) movement would be the one for this watch. I'm feeling fairly confident that I could do the movement swap, but this will be the most ambitious project to date. I anticipate the hardest part will be resizing the stem in the new movement to fit the watch. I will also need to order a pin vice when I buy the movement to remove / replace the crown.  
Understand that this watch has some sentimental value for the owner, far in excess of its true value - though I won't tell him that. Also understand the owner is retired, so cannot afford to pay the silly prices a high street watch repairer is likely to charge. I really would like to restore this watch for my friend as cheeply as possible, so I would welcome any advice that the members here could give. Am I being over confident?