C25A Captain reported thumping noise with erratic hydraulic pressure and landing gear unlock indications resulted in divert due to incorrectly installed part.

Narrative

Not long after rotation; the Hydraulic Pressure light started flickering on and off and the red Landing Gear Unlocked light started flickering. While first officer pulled the checklist; I checked to ensure the gear handle was up because once before I had seen this issue and the gear handle was not fully up. I wriggled it slightly upwards and a few seconds later; the lights extinguished. I felt it was simply the gear handle hadn't gone completely up (despite there being very little movement upwards). As we went through transition altitude; first officer and I both thought we could feel a very small vibration but there was no indication of any abnormalities. I didn't feel completely sure that the problem had been resolved because of how little the gear handle moved so I called [maintenance] from the air and he told me that the gear up lock roller had been worked on. Given that there were no further indications of any issue; we elected to continue the flight.We leveled off at FL350 and there were no indications of any abnormalities. For our initial descent into ZZZ; we were cleared to FL310 with an expedited descent. Upon leveling off at FL310; a loud thumping commenced from the nose of the aircraft. Because of the initial issue after takeoff and my discussion with Name; I immediately slowed down to 200 knots and lowered the gear. As soon as the gear extended; the thumping immediately stopped. I then retracted the gear; and the thumping immediately returned. Given our altitude; I elected to request priority so we could descend immediately and then slowed up to 175 knots and lowered the gear. I know we were above 18;000 feet for gear extension; but I felt that the right decision was to lower the gear given the loudness of the thumping. The intensity of the noise sounded like it would damage something if left for any time. Given the unknown status of the gear; I elected to divert to ZZZ1 airfield due to the longer runway available; the considerably less congestion; and our familiarization with the field.My main concern was the condition of the nose wheel; so we conducted a low approach and had tower check the gear extension and the direction of the nose wheel (I wanted to be as informed as possible about the gear even though everything felt right and was indicating correctly; i.e. gear extension lights were three green and no red and there was no unusual rudder control required.) Tower confirmed everything looked okay and so we then proceeded to land. We flew the V speeds all the way in; landing with flaps 35. Upon touchdown; I held the nose off initially and just gently touched it on the runway to ensure directional control; and then again held it off for a little longer to protect it if it had sustained any damage. Once slowed sufficiently; we gently came to a slow roll with minimum braking using about 60% of the runway (from the threshold to taxiing off).We kept the passengers briefed throughout the situation and advised them that we were acting in a precautionary manner. Only one passenger seemed emotionally concerned. Upon egress after the event; all pax seemed in good spirits.The nose wheel up lock bracket was installed upside down. Additional inspection of maintenance work after completion.