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Angled Valve stems £11 at http://www.ebay.co.uk/itm/251294653151

For battery replacement, don't bother trying to find one with suitable tabs:

• There are none available with solder tabs at the right angle so you'd have to bend and bodge what you find
• The bulk of any tabs that have been bent around to fit will make it difficult to close the cover on the module
• The profile of the tabbed version will have square or only slightly chamfered bottom edge and wont fit the casing

Buy vanilla CR 2032's with the standard chamfered profile on the bottom edge. Use some fine sandpaper to key the surface of the battery at the points on positive and negative sides roughly where the terminals will be connected ( on clock face, lets say 10 to 10).

Prepare two lengths of small gauge wire measuring about 10mm and tin each end. Tin the points on the battery where these wires will be attached, use a lower power soldering iron and limit the heat at the solder point as much as possible to avoid damaging any internal components of the battery. I found that I only needed the lightest touch to tin the battery,  and you will not need to put more than a 2mm blob to secure, provided that you properly keyed the surface first.

The rest is plain sailing. Solder the wires on the battery and then onto the circuit board terminals. I soldered wire to terminal pointing away from the battery compartment so I could lose any excess wire in the terminal channels.