Master Spa LSX 1050 questions

[Yooperboy877]

Hello.  We're in the process of buying a house that includes a 2006 vintage Master Spa LSX 1050 spa.   I've owned spas in the past (a Sundance Cameo that I purchased myself, and a Tiger Spa that came with another house), so I have some general knowledge about maintenance, etc., but am new to Master Spas.  This might not be a unit that I would purchase new, and my tolerance for expensive repairs and operation is relatively low, but it's essentially free at the get-go, so I'll run with it.  I do, however, have a couple of questions that I've been unable to find answers for, and hope that someone here can help out:

a.  The cover on the spa (a four piece unit) appears to be original, and in any case needs to be replaced.  Masterspapartsonline.com wants $800 for the replacement, model MSCOVER10.  I need a 4 piece unit, as I have two cover lifts on either end.  However, the alternate vendors I've found all appear to be pushing two or three piece units.  Any suggestion for an alternate vendor for a 4 piece cover?

b.  Can anyone provide me with a parts schematic for the shell and all of the attachments, through-shell items, etc.?  I have some pop-up items that do not appear to be functioning properly (they won't go down and stay down!), and will likely need to replace them.  They don't appear to be speakers, and I have not been able to find anything that looks like them on line?

c.  I believe this spa is running on chlorine.  My prior experience has been with Baqua (on the Sundance) and bromine (on the Tiger Spa).  Anything I should consider if shifting to either one of these treatment regimens?

Many thanks for the responses and guidance!

James Holden