@ Alexender there are some ...
Published by Water Network Research, Official research team of The Water Network
@ Alexender there are some documents in the group library about troubleshooting and maintenance of hand pumps of different make. You may like to have look, http://bit.ly/QjVzzE https://water.tallyfox.com/documents/handpumps https://water.tallyfox.com/documents/hand-pumps-how-repair-common-problems