Non-bendy couplings

This afternoon I tried to run an LGB coach in front of a Piko BR80 and the blessed thing stalled on every sharp curve (1s and reverse 1s) the coach is fitted with an LGB scrubbing rail cleaner. Normally this branch line is run with the same coach and a Stainz (bless their little cotton socks). The branch line has a steep incline which means the loco (prototypically) pushes the carrriage up and brakes it coming down.
I got the track cleaning super rubber out, but no; stall, stall, stall. Only on bends, not on straights.
After watching for a little while it occured to me that the coupling of the loco was fixed, whereas the coach 'floated'. I took the BR80 off and peeked underneath: the couplings are body  mounted with little give, and behind the coupling is a sort of 'V' to keep the coupling straight. The front one seemed to be tighter than the rear which could mean it effectively put too much drag on itself and stalled.
Question is has anyone else had the same problem, and can I cut off th 'v' to allow more sideways movement without detrimental effect? Or can I simply loosen the screw holding the front coupling and carry on?

I was wondering if I'd strayed onto a different forum with a thread title like that!

Oh, are you a member of that forum too? Cheeky monkey

Try the loose screw idea first?

Nothing to loose....

Gizzy

Try the loose screw idea first?
Nothing to loose....

Except the tiny winy tiddly piddly likkle screw somewhere in Luxembourgs answer to the Amazon forest.
Any jokes about me being a screw loose will be met with a thump.

It looks like I'll try tomorrow, Disco party here tonight - where are my white slipons?

pugwash

Any jokes about me being a screw loose will be met with a thump.

We didn't have to mention it, you did it all yourself!

I had the same problem with the piko 6 wheel diesel.  yes the plastic centring spring  is too strong.
solution is to use a small pair of pliers and bend each leg of the spring to the centre. if you do it carefully it will not break.  set them almost touching so that when it swings over it can almost go right across from side to side.   hope you can understand my description.
 
gep4 

Zman

pugwash

Any jokes about me being a screw loose will be met with a thump.

We didn't have to mention it, you did it all yourself!

Thump!

gep4

I had the same problem with the piko 6 wheel diesel.  yes the plastic centring spring  is too strong.
solution is to use a small pair of pliers and bend each leg of the spring to the centre. if you do it carefully it will not break.  set them almost touching so that when it swings over it can almost go right across from side to side.   hope you can understand my description.
gep4 

Hmm, good idea falls inbetween losing bits and total destruction, but the plastic used seems to be inflexible. How about warming before bending? Like a quick blow over with H's hairdryer to soften things up?
And to be honest why not cut the ruddy things?

Update:
bending didn't work, nor did the loosening of screws.
From the coupling going back are two prongs with a V form, at the back end of each prong is a square section, these sit between guides to stop the coupling swinging too far to one side or the other. The plastic used for these prongs is too hefty especially towing something with a bit of drag around R1s.
After a quick guesstimate I cut off the square end sections as it looked as though without them there would be sufficient play, and if not I could shorten the V prongs until there was. It worked, I only had to cut off the square sections and everything ran perfectly.
Now, what will go wrong next?