Thank you for that information @GrayGhost… 
I am going to give this a go, I
bought a Select “In” via eBay, knowing full well, the battery was goosed, I was struggling to get a couple of your suggested 503030 3.7w 450 mAh LP batteries, I could get them, but it was a couple of weeks turnaround, so I am going to try the 503035 500 mAh, hopefully these will still fit? I have all the installation equipment required already, including a LPG soldering station… The batteries should arrive in a couple of days time, I bought a spare, as I have another ordinary Select I acquired a while back… I have already done a “Select In” tear-down & rebuild, to see what I am dealing with… I am much obliged for your information, I will report back… Cheers Kev