I recently posted some photos in this from that I took with my Olympus PEN, trying to figure out why they looked soft. One of the suggestions was that perhaps when it was repaired / cleaned, someone disassembled the lens and didn't put it back at quite the right distance from the film.
Absolutely. Very likely to be the reason.
My own experience regarding this: I lusted for years after a Rolleiflex. I finally found a 3.5F III with the last Planar version in what seemed like mint condition. Original case in good condition, 'one careful owner'. I went through the images with a fine comb. I bought it.
Initially impressions were good. No fungus, no dust, no mould or other crud in the taking lens. I go test it with film. The images didn't impress me
at all. They looked, weird, soft, 'low-fi', just like most of the Rolleiflex images you see online. But
I knew I should get something better, as I have an almost new Rolleicord (Xenar lens) with a known 'pedigree' that gave me much sharper pictures than the Rolleiflex.
So I bite the bullet and decide to send my 3.5FIII to the best Rollei repair wizard currently on the planet - Magicflex in Germany. He essentially rebuilds Rolleiflex bodies from the ground up, has access to original bits and pieces, and doesn't mess around - but it will cost you. Also, he has access to original Rollei test equipment which he uses to critically measure tolerances to the same standard -or better- used by the original Rollei employees when building these. At the moment, he only offers his own rebuilds for sale at astronomical prices. Back then, a few years ago, he accepted other people's Rolleis for full rebuilds.
So he starts rebuilding mine from scratch and he keeps me posted with texts and images about everything that he found. A lot was wrong with the camera. A lot. I won't give you details to avoid boring you to death but this camera had been tampered with by a few clueless people. Owners? Possibly. Experienced 'technicians'? Very likely.
When he gives me the camera back, I had a somewhat lighter wallet but a completely new camera. It felt different, smelled different, worked different. Most importantly it takes images that are leagues better wrt what I was getting before. The scans (4000dpi scans from my Nikon Coolscan) look like from a different camera essentially.
Again: the camera looked new. None of the usual yellow or red flags. I even carefully went with a ruler through the images to make sure the front standard wasn't misaligned!
What this has taught me is that dicking around with used gear can be an expensive, lengthy pursuit best left to people who have the time and money. Myself, I just want a perfectly working tool to take photographs, and next time I will only buy a new camera, so all I can say is I hope Pentax delivers.