Trim tab problems

[wheresmybobber!]

So when I bought my boat the previous owner said that he had put in a brand new Bennett 351 pump and all the hardware not to long before he dicided to sell the boat. He told me that he didn't think the switch was working so I would just need to put a new switch in. Well I've gone through and put new switches in and still can't get them to work. I have plenty of fluid in the res. and I can hear the pump working when I hit the switch but I can't get the trim tabs to go down. I can manually push on the tabs and get them to move so my question is, do I need to purge the system for any possible air in the lines or am I just missing something all together?

Thanks in advance

Mike

[riverhawk]

Could the pump be running backwards. It should be self purging if has oil in it.

[jet2go]

My Bennett tabs manual said to extend the tabs all the way down then all the way back up a total of three times to purge the system. It seemed like I had to do it more than 3 times, but eventually all the air was out of the lines.