Celestron130/f5 project

[Alfian]

I have dug my old Celestron 130 ota out and feel as if I ought do something with it one way or another. I am glad of it as it got me going, so to speak. However it got me going in another sense too so I tend to look back on it mainly with frustration. Whats his name finding work for idle hands and all that, I thought I might see if I can make a more usable scope of it or ditch it. I overhauled the focuser several years ago and despite its silly plastic shroud it runs pretty smoothly so I am happy with that. The front cell with the attached secondary is a problem. The thick plastic non adjustable spider is horrible, so the only alternative is to replace it. Astroboot have had over some time various mirror sets for sale at useful prices but at the moment the only one I can see is a front cell for 130/900 ie f6.9. I realise that an f6.9 primary will not work in the scope, and please excuse my ignorance, but with a secondary being "flat" would that work in the f5?  Incidentally now its all stripped down to the last nut and bolt I can see that the secondary mirror mounting bolt is slightly off centre. I've measured it round and its off by just over 1mm. I realise there is a small offset on the secondary and i'm not sure whether its connected in this respect but this seems offset across the wrong aspect of the mirror mount. Ho-hum. Its probably more trouble than its worth but would appreciate any advice. If a moderator thinks this should be in DIY then please move it. Thanks.