The endcaps of the solderless power tubes can be damaged in hard crashes when the battery pack is ejected from the helicopter. These endcaps can be purchased separately from MEC.
My experience with the SPT battery packs is the battery terminals tend to oxidize as the batteries are heated and cooled. This oxidation results in increased resistance and the battery pack may appear to be weak.
I recommend disassembling the SPT battery packs about once a year and inspecting the battery terminals. If the positive terminal has a thin film of white residue on it, then this is a sign the cell has vented. This indicates the cell is probably weak. You should clean the terminal and write a mark on the cell to indicate it has been cleaned. If this cell requires cleaning more than once, it should probably be replaced.