Empying crop / vomiting

[shell3]

Hi everyone, i have a hen with ongoing crop problems , my thread is 'sour crop' hens name 'Bombie'
Ive been given great advice on that thread and had lots of support but what im looking for is some good advice and instructions on emptying the crop as safely and efficiently as possible.
she has been eating feathers and is not emptying the crop herself.her health will get worse quick if i cant get a handle on this!
my vet has tried to empty it today as i was struggling this time around. he got some but not all the contents out so now its down to me to get it clear in the next couple of days.
i think tubes are not going to work because the feathers wont come out that way.
i would love someone to describe to me exactly how they do it. ive heard that you should lift them up every few seconds to breathe but also heard you should keep them down until all liquids out to prevent fluid from travelling backwards and into the lungs!
the fluid in her is thick and gloopy and full of feathers, any opinions on the best way to go about this are very welcome. as are tips like maybe filling her with warm water first?? i dont want to dehydrate her with any thing like epsom salts as im not sure how much water is going down.
thanks shell
xx