Should I Attempt? - tag heuer stem/crown

[GLENGRAVING]

I'm a watch-battery-replacer,  tentatively looking to learn about watch glasses / movements. As such, when my cousin told me about his broken watch, I said I'd have a look. 
Not sure what happened but the crown is missing, possibly snapped at the stem. Problem is that this is a Tag Heuer Formula 1 Grande Date, pricier than I'd like to learn on (and with no real profit to the job as it's for family).  

I looked at the movement and it's a "RONDA 5040.B", which takes a Ronda 3000.177 Stem, according to google/cousins. 

Not sure which crown to order; Cousins have a few Tag Heuer crowns listed, not sure how to pick the correct one for the stem/case. Also the original was black - it's on ebay but the price is hefty. 
Thoughts? 

 

[Mike at Vauxhall]

You've  said it yourself, "pricier than I'd like to learn on". Start off on the cheaper watches, tell your cousin to take it to a Tag dealer, he's got an expensive watch, with that come expensive repairs. Hate to be pessimistic, but you could get your fingers burnt. 

[grahamparker]

Do not touch it unless your prepared to replace it. Always amazes me how many people pay for a really expensive watch but try to cut corners on service and repairs. Get it repaired by an authorised repair centre so you cannot be accused of doing any further damage.

[Mike at Vauxhall]

1 hour ago, grahamparker said:

Do not touch it unless your prepared to replace it. 

Great quote, and really sums up any potential liability. I will be using it in the future.

[GLENGRAVING]

Thanks for the advice, it just seemed like such a simple job, provided I had the right part

[Count Muppet]

6 minutes ago, GLENGRAVING said:

Thanks for the advice, it just seemed like such a simple job, provided I had the right part

It is if you have the right part but the part is missing and you aren’t 100% which part it should be

those shown on eBay mention that they may be a different version from the original so you may have to change the screw in tube also. It starts to get a bit more complicated and expensive the more parts need doing and adapting.