I'm going through the process of collimating my telescope for the first time and am finding that the position of my secondary is not close to centered in the sight tube when I "center" the secondary holder in the OTA by ensuring that all spider vane lengths are equal. The photo below illustrates what I mean. Note that in this photo all of the spider vane lengths have been adjusted to be equal in order to perfectly center the secondary holder in the OTA, yet the secondary appears off center as seen through the sight tube. I have also centered the secondary in the up/down tube axis (as seen through the sight tube) using the center screw on the secondary holder.
I've done quite a bit of research on this, searched all forums, reddit, and have read through all of the recommended guides and it seems that everyone more or less assumes that the secondary will be centered "across" the tube and only advises to center in the up/down tube direction using the center screw on the secondary holder. Some guides mention to "center" the secondary using the three tilt screws, however my understanding is that these are used to "point" the mirror and not position it so that it is well-centered under the eyepiece (maybe I'm wrong here but I don't see how it would be possible to correct the offset I'm seeing by adjusting the tilt screws). Some guides have mentioned to adjust the spider vanes in order to center under the eyepiece but when I do this the secondary holder is clearly offset in the OTA as can be seen in the photo below. Note that the thread engagement is very different on the cross tube vanes and the secondary holder is 1/8" - 1/4" off center in the OTA - this seems to contradict almost every guide I've seen which always starts by instructing to perfectly center the secondary holder in the OTA.
I've also read a lot about how secondary mirrors are supposed to be offset in fast scopes (this scope is f/5) - however I believe that is referring to something else entirely - correct me if I'm wrong but the outline of the secondary SHOULD appear concentric with the sight tube, correct?
I've tried shimming the focuser but even this is not enough to center the secondary in the sight hole - even when I shim the upper side of the focuser to the extent of what the threads will allow. To shim any more I would actually need to get longer screws - and it seems like I'm shimming beyond where the focuser would be perpendicular to the tube.
So in short, my questions are:
1: Does it even matter if the secondary is centered as seen through the Cheshire sight tube in the "cross" tube direction?
2: If #1 is critical then what is the recommended method to center the secondary in this axis? Is it acceptable for the spider vanes to be unequal in length thus placing the secondary holder in an off-center position in the OTA?
3: Is there something else at play here that I'm missing? Possible poor placement of the secondary mirror onto the holder or something else?
4: Is shimming the focuser until everything is physically centered the answer - even if it is no longer perpendicular to the OTA?
Thanks for bearing with me - I know this is a long post and hopefully I've explained well. I've been driving myself crazy trying to achieve proper collimation and nothing seems to work or make sense at this point. Feel like I've scoured the internet looking for an answer so if I've missed some other guide or post that explains this well then please point me in the right direction.
Any advice is very much appreciated.