A frugal life is an easy life!

Looking around for a wide angle, manual lens for my 70d, I was drawn to the OM range of lenses, which many baye sellers claim can be adapted to fit my camera.

So after much research into picture quality, etc, I opted for an Olympus OM G.Zuiko 28mm f3.5 wide angle lens.

Ideal I thought. Reasonable price, easy to adapt and great for pics and filming.
I picked one up cheap, in great condition. Ordered the adapter from a UK seller and waited for them to arrive.

It came today and the lens is ace.
However, the adapter is the problem.
It has a pin inside the adapter ring, which is designed to hold the aperture preview spring loaded lever, to open position.
Problem is, the pin stops before the lever when fitting the adapter, so basically, does absolutely nothing.
I've tried unsuccessfully for hours to get it to work, changed the way I fit the adapter, etc. Nothing has worked.

Perhaps I've bought the wrong one?
Nope, all the ebay listings show the same layout of adapter, along with advertising that it works with the Canon 70d. It does not.

When the lens is on the camera, it is wide open at f3.5 with an aperture preview button to the bottom of the lens, that when pushed allows the lens to be stopped down to f16.

Problem 1:
If control of aperture can only be accessed by pushing a button, how can you possibly know which f stop number is in use?
Problem 2:
Having to push this button at the same time as focusing and the shutter button is problematic for the user.
Problem 3:
Using the canon 70d and this lens with a tripod is not possible. As the base of the lens is where the button is situated, then access would be denied to it, when the tripod plate is on the camera.
Problem 4:
What does the insert pin actually do? It comes into no contact with either of the spring levers inside the rear of the lens.
Problem 5:
As this aperture preview button is at the base of the lens, it makes it completely useless for filming with the 70d.
Problem 6:
To do any filming, would have to be at f3.5 (wide open) and hand held.

I really wish that this misleading advertising was stopped.
It does not work with the Canon 70d.

UPDATE:

I took the lens apart to try and negate the spring clip, that the adapter's pin was stopping before.
I took the spring out, tried it.
Put the spring back in, tried it.
I put tape around the silver plate of the lens, to hold the preview button in, tried it.
I bent the pin of the adapter slightly upwards, bingo!

I got another bit of turn from the adapter and the spring preview clip is pushed across to allow manual changing of the aperture ring.
I must have had a slightly raised rear cover of the lens which prevents the adapter from going all the way around. It remains a very tight fit, so if I want to use another Olympus lens with the camera, I'll have to buy another adapter.