James and Luis, I have only now seen your posts and should like to give some answers.
Although available for little money today the Paillard-Bolex H are cameras for the engaged amateur and retain a useful value of several hundred Dollars. The point is that they should be understood and maintained.
As a professional motion-picture film equipment service person, a trained mechanician, and longtime technician with cinemas and labs let me give you the following advice. Have your camera overhauled by someone that has the necessary instruments and experience. One can easily bring damage to an H, if tinkering about. To have a look inside won’t help the layman because he doesn’t know what to check. Not that I wanted to disapprove anybody’s mental capabilities and dexterity. It simply takes the knowledge of some years of work with fine mechanical apparatus in order to service a film movie camera correctly. Don’t you want to be able to rely on the camera when shooting expensive film?
Very broadly speaking a complete service job on an H-16 takes about four hours of work. Since I take 90 Swiss Francs per hour you would look at initial costs of 360 Francs (around $360 today). Please believe me, that money is well invested. Your camera will return cleaned, freshly lubricated, and adjusted in every way, within some boundaries also according to your personal needs. Here I mean the frame rate which can be predominantely adjusted for the lower or the middle section depending on whether you shoot at silent or sound speeds. The initial idea was to offer fine tuning between 24 and 8 frames per second, still more differentiated than what the Ciné-Kodak Special offered at the time.
Of course can you start cleaning the focusing prism with a cotton swab moistened with some alcohol. It is accessible for that. Still I’d like to suggest you have the camera gone through and measured. I have found displaced prisms, even mechanical parts from manufacture out of tolerance (yes!). I think everybody wants the certainty that the flange distance is within specifications. Else, no lens can deliver sharp images.
Speaking of lenses, there is no need to spend ridiculous amounts of money on optics that have become the victim of a craze. Traditionally you have Kern-Paillard lenses with Paillard-Bolex equipment. The Yvar 75 mm, f/2.8 for example has lift off the ground of common sense. Never pay more than $300 for one of these unless it’s been serviced by someone who knows the stuff and grants a warranty on her/his work. After all, it’s only a triplet. The 100 mm and 150 mm Yvar are offered at entirely mad prices, up to $2,400. Stay away from that. Wide-angle lenses, most often consisting of six to eight elements, may cost more. The Kern Switar 10 mm is good but other makes are nice, too. I can recommend Schneider, Rodenstock (if you happen to stumble over one), Voigtländer, Zeiss, Leitz, Taylor-Hobson Cooke, Angénieux, and a few American ones. Berthiot are interesting, too, with some exceptions due to poor iris mechanics. Kinoptik can be had second-hand, individually matched elements lenses, therefore expensive but excellent.
Most every lens manufacturer made different versions of a focal length. With Kern-Paillard we have four possibilities at normal focal length for the H-16 Standard:
- Yvar 25 mm, f/2.5; triplet
- Yvar 25 mm, f/1.8; four elements
- Pizar 26 mm, f/1.9; five elements
- Switar 25 mm, f/1.4; six elements
Same goes with the double focal length where we have the Pizar 50 mm, f/1.8, a five-elements design, and the Switar 50 mm, f/1.4. This one is the bigger brother of the Switar 25-1.4, similar to it but not quite the same. A Schneider Xenotar or Xenon belongs to the higher class as well, you will have beautiful images from them. Among the American optics Bausch & Lomb and Wollensak are preferable to Elgeet, Ilex, and others. Bell & Howell never made lenses themselves, they’re Wollensak, TTH, Meyer, later on from Japan.
Finally, do yourself the favour of not misusing the turret concept of the H-16. It is there for a choice of prime lenses, not for a zoom. With the relatively compact and lightweight fixed focal length optics you have a maniable camera system. Additional lenses are best carried along in a rugged case. A lens may also be in terrible need of an overhaul. Never force lens rings, you can badly damage the diaphragm. That’s why some diaphragm leaves are found derailed today, people twisted them kaputt. They can stick together heavily by dried oil.
The diagonal rackover accessory belongs to the standard H camera. Check the internet trades, it can be had inexpensive. The most important accessory you should use, though, is a tripod.
but does also have the trifocal contraption on the side). 
, but I don't want to ruin a $50 spool of film either.