I have just aquired T1400 pro, and i wont call summa cutters as i love them my previous one was a D60 and yes i had a replacement head once because of the sticking head syndrome, (wish i had used the pad trick) but now with the same thing happening to the tangential cutter i am trying to solve this as i aint paying £900 for a head fitted.
I bought the machine for £450 thinking it needed a new head and thought i would take a risk, i competely stripped the machine as it had been stood in a bodyshop for 2 and a half years, including removing the head.
Now when you remove the head on these machines, you must mark the height on the carriage, and put the head back in the same position theres just 3 screws holding it to the carriage plate, which dont have to be removed fully just slackened off, you must remove the circuit board and disconnect the drive motor wires from the circuit board, a good tip here is if you do remove the belt to the coil then make sure you mark up the blade holder and wheel on the motor as when its sets itself to zero, to start a cut you must make sure that the blade is in line.
I am going to remove the head on mine and turn it upside down and give it a good spray with (Ipa) Alcohol, and let it run down the inside of the cast iron drum leave it for ten minutes whilst working the head up and down and then turn it back over to let the ipa drain out and dry. This should get rid of the sticky lip, of which i am told happens to lots of solenoids, not only in cutters, also be careful of using oil like wd40 or 3 in 1 as dependant on the consistency it can work like a seal and create a vacuum when the coils going up and down and can actually make the sticking problem worse.
Also dont forget on these summa tangential cutters, the blade on the T knife doesnt go all the way in and tighten up to hilt, for a normal T knife when new set your pressure to around 70g, then slowly wind your knife in quarter turn at a time till you get a clean cut, without going through the backing, if you are having the starting problem then wind your pressure up to say 140g, and set your knife blade again it should cut fine at the start, till you can get chance to take a look at it.
I'll let you know how i get on