Hello,
it seams to me that the confusing Czech manual has been translated into confusing German manual.
Let me explain how the TK14 lubrication system works that will explain everything.
TK14 oil pump has two pistons and two lubrication circuits
1. Oil from oil reservoir gets injected into the cylinder bellow the exhaust port. (That is the primary circuit)
2. Unused oil goes through the mesh at the bottom of the crankcase and gets sucked from there through the Filzfilter back into the oil reservoir. (That is the secondary circuit)
So if you cleaned out the pipes you wont get any oil at FilzFilter for a while.
Now how to properly test it:
1. remove the exhaust muffler
2. disconnect the oil line under the exhaust cylinder port
3. remove Lunte holder and spin the engine with a starter
4. if working correctly oil will drip at about few drops a minute.
If you secondary circuit fails you will just get lots of smoke from oil rich mixture, clean it, verify its working once and dont worry about it.
You can also test the oil pump removed in a big jar with oil, spinning it with a drill. Exact values of oil delivery are in the manual. just need to recalculate for drill RPMs.
Does the glow plug have chamfer at the end to seal into the cylinder head just like the lunte-holder does?
Hope it helps.